PLATE I. 



Fig. 30. 

 Fig. 31. 

 Fig. 32. 



Fig. 33- 



Sagitta Bedoti Bcraneck. 



— The entire animal. 



— The head, showing the corona ciliata, and some of the patches of sense cells. ■ 33. 



— A jaw. / 105. 



— The tip of the youngcst (most anterior) jaw. / 430. 



. — ■ The tip of an older jaw. X 430. The extreme tip has bcijn drawn too squarcl)- blunt. 



— The anterior teeth, boiled out. < 140. 



— The posterior teeth, boiled out. ■' 140. 



— The vcstibular ridgc, showing the position of the externmost tooth belovv the terminal process.XHO. 



Sagitta etiflata Grassi. 



— The entire animal, from a rather slender specimen. 



— 13. — The anterior end showing different forms (or distortions) of the corona ciliata: its front 

 end lay under a fold of the prepuce, but appeared to have the form indicated by dotted 

 lines in figure 10. (Fig. 10, < 13; 11, X 25; 12, X 20; 13, X 25). 



— A jaw. -71. 



— The anterior teeth, drawn in place. • 140. 



— The posterior teeth, drawn in place, wilh the vestibular ridge : dorsal view. X 140. 



— The vestibular ridge, ventral view. 140. 



Sagitta fcrox Doncaster. 



— The entire animal, from a specimen of medium size. 



— The entire animal, from a large specimen, showing the streng development of the collarette. 



— The anterior end of the animal, showing the e.xtension of the corona nearly to the ganglion. 



The irregularities at its anterior boundary vary in different specimens. • 33. 



— A jaw. X 71. 



— The teeth in place, from a transparent specimen. X 140. 



— The posterior teeth and vestibular ridge: dorsal view. x 140. 



Sagitta hcxaptera d'Orbigny. 



a. Hcxaptera formula. 



— The entire animal (formula, 6:3:5 — 6). 



— The distal end of the newest jaw, the anterior and posterior teeth (formula, 8:3:6). X 105. 



— The distal end of the newest jaw, one anterior tooth in exact profile, and the posterior teeth 



(formula, 9 — 10:3:2- — 3). ■. 105. This formula is nearly that oi magna. 



— Part of the vestibular ridge; dorsal view (formula 5:3:4). •' 140. 



b. Tricuspidata formula. 



Fig. 34. — The entire animal (formula, 5 — 6:3:3). 



Fig. 35. — The corona ciliata (formula, 4:3 — 2:2). x 25. 



Fig. 36. — The distal end of the newest jaw (formula 5 : i : i), the anterior and posterior teeth (formula 



4:2:1). X 105. 

 Fig. 37. — I'art of the vestibular ridge (formula, 8:4 — 2:3—1). ■ 105. 



c. Magna formula and inagiia from Naples. 



Fig. 38. — The entire animal, from a Naples specimen. 



Fig. 39- — The corona ciliata, from a Naples specimen. ■ 12. 



Fig. 40. — The distal end of the newest jaw, the anterior and posterior teeth (formula, 4:3:2 — l). X 105. 



This formula is nearly that of tricuspidata. 

 Fig. 41. — Part of the vestibular ridge, with the teeth in place (formula, 9:4:3). ■ 105. 



Sagitta neglecta Aida. 



■ The entire animal. 



■ The anterior end, showing the corona and collarette. x 33. 



■ The anterior end, showing a rather longer corona, the abdominal ganglion, and the tactile 

 prominences: of the lattcr only the larger wcre drawn. ■ 33. 



A jaw. .- 43. 



■ The anterior teeth in place, slightly foreshortened. X 2IO. 

 The posterior teeth in ])lace. 210. 

 The corona ciliata with the externmost tooth. • 210. 



