ClipArt ETC
"Diagram of the metamorphosis of the free, tailed larva into the fixed Ascidian. A, stage of free-swimming larva; B, larva recently fixed; C, older fixed stage. adh, adhesive papillae; atr, atrial cavity; cil. gr, ciliated groove; end, endostyle; ht, heart; med, ganglion of trunk; n. gn, nerve-ganglion; noto, notochord; or, oral aperture; rect, reectum; sens ves, sense vesicle; stig, stigmata; stol, stolon; t, tail." -Parker, 1900

Ascidian Stages

"Diagram of the metamorphosis of the free, tailed larva into the fixed Ascidian. A, stage of free-swimming…

"Development of excretory system of vertebrate. The primitive segments are not separated off from the lateral plate, and the pronephros (pn.) is seen arising from the lower part of the primitive segment. n.c., nerve cord; nch., notochord; pn., pronephros; g., gut; p.s., primitive segment; mes., mesonephric tubule; pn.d., pronephric duct; b.c., body cavity; ao., aorta; siv., sub-intestinal vein, with vessel to the aorta." -Thomson, 1916

Excretory System Stage 1

"Development of excretory system of vertebrate. The primitive segments are not separated off from the…

"Development of excretory system of vertebrate. The pronephros is completely separated off from the primitive segment and lateral plate. n.c., nerve cord; nch., notochord; pn., pronephros; g., gut; p.s., primitive segment; mes., mesonephric tubule; pn.d., pronephric duct; b.c., body cavity; ao., aorta; siv., sub-intestinal vein, with vessel to the aorta." -Thomson, 1916

Excretory System Stage 2

"Development of excretory system of vertebrate. The pronephros is completely separated off from the…

"The origin of the mesonephric tubules is seen. They arise from the upper part of the lateral plate, which is now completely separated from the primitive segment, and curving round the pronephric duct come to open into it. n.c., nerve cord; nch., notochord; pn., pronephros; g., gut; p.s., primitive segment; mes., mesonephric tubule; pn.d., pronephric duct; b.c., body cavity; ao., aorta; siv., sub-intestinal vein, with vessel to the aorta." -Thomson, 1916

Excretory System Stage 3

"The origin of the mesonephric tubules is seen. They arise from the upper part of the lateral plate,…

This is a diagram of the cross section of a fish, showing the bilateral symmetry of the parts: dv, dorsoventral axis; vl, right-left axis. a.p., anterior appendage; b.c., body cavity; ch, notochord; d.f., dorsal fin; g, gut; h, heart; h.a., haemal arch; m, muscles; n.., neural arch; sp, spinal cord; v.c., vertebral column.

Fish

This is a diagram of the cross section of a fish, showing the bilateral symmetry of the parts: dv, dorsoventral…

"Lateral view of Amphioxus. The notochord runs from tip to tip. t., Tentacular cirri; G., reproductive organs; a.p., atriopore; a., position of anus; 40 and 62, indicate number of myotomes." -Thomson, 1916

Lancelet

"Lateral view of Amphioxus. The notochord runs from tip to tip. t., Tentacular cirri; G., reproductive…

"Section of <em>Ampioxus</em>, fr, fin ray; ct, connective tissue; nc, notochord, ; snc, supraneural crest"&mdash;Finley, 1917

Section of a lancelet

"Section of Ampioxus, fr, fin ray; ct, connective tissue; nc, notochord, ; snc, supraneural…

"Side view of <em>Amphioxus</em>: fs, fin supports; nc, notochord; ot, oral tentacles."&mdash;Finley, 1917

Side view of lancelet

"Side view of Amphioxus: fs, fin supports; nc, notochord; ot, oral tentacles."—Finley,…

This is a diagram of a trunk vertebra in a mammal. c, centrum; ch., position originally occupied by the notochord; h., head of the rib; h.c., haemal cavity; n.a., neural arch; n.c., neural canal; n.s., neural spine; r., rib; st., sternum; s.c., sternal cartilage uniting ribs and sternum; t.p., transverse process of vertebra; tu., tuberole of rib.

Mammal Vertebrae

This is a diagram of a trunk vertebra in a mammal. c, centrum; ch., position originally occupied by…

"Lateral view of caudal vertebra of Basking Shark (Selache mazima). a, centrum; b, neurapophysis; c, intercrural cartilage; d, hemapophysis; e, spinal canal; f, intervertebal cavity; g, central canal for persistent portion of notochord; h, hemal canals for blood-vessels." &mdash; Encyclopedia Britannica, 1893

Shark Vertebra

"Lateral view of caudal vertebra of Basking Shark (Selache mazima). a, centrum; b, neurapophysis; c,…

"Longitudinal section of caudal vertebra of Basking Shark (Selache mazima). a, centrum; b, neurapophysis; c, intercrural cartilage; d, hemapophysis; e, spinal canal; f, intervertebal cavity; g, central canal for persistent portion of notochord; h, hemal canals for blood-vessels." &mdash; Encyclopedia Britannica, 1893

Shark Vertebra

"Longitudinal section of caudal vertebra of Basking Shark (Selache mazima). a, centrum; b, neurapophysis;…

"Transverse section of caudal vertebra of Basking Shark (Selache mazima). a, centrum; b, neurapophysis; c, intercrural cartilage; d, hemapophysis; e, spinal canal; f, intervertebal cavity; g, central canal for persistent portion of notochord; h, hemal canals for blood-vessels." &mdash; Encyclopedia Britannica, 1893

Shark Vertebra

"Transverse section of caudal vertebra of Basking Shark (Selache mazima). a, centrum; b, neurapophysis;…