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PLATE I. 



Sagitta Bcdoti Beraneck. 



— The entire animal. 



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



— A jaw. ■ 105. 



— The tip of the youngest (most anterior) jaw. ■ 430. 

 • — The tip of an older jaw. X 430. The extreme tip has been drawn too squarely blunt. 



— The anterior teeth, boiled out. X 140. 



— The posterior teeth, boiled out. X 140. 



— The vestibular ridge, showing the position of the extern most tooth below the terminal process. X140. 



Sagitta enflata 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, X 13; n, X 25; 12, X 20; 13, < 25). 



— A jaw. • 71. 



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



— The posterior teeth, drawn in place, with 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 strong development of the collarette. 



— The anterior end of the animal, showing the extension 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. 140. 



Sagitta lux apt era d'Orbigny. 



a. Hexaptcra formula. 



Fig. 30. — The entire animal (formula, 6:3:5 — 6). 



Fig- 31. — The distal end of the newest jaw, the anterior and posterior teeth (formula, 8:3:6). X 105. 



Fig. 32. — 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 of magna. 

 F'g- 33- ' — F art °f tne vestibular ridge; dorsal view (formula 5:3:4). X 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 5:1:1), the anterior and posterior teeth (formula 



4:2:1). ■ 105. 

 Fig. 37- — Part of the vestibular ridge (formula, 8:4 — 2:3 — 1). • 105. 



c. Magna formula and magna 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 — 1). 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). x 105. 



Sagitta neglecta Aida. 



Fig. 42. — The entire animal. 



Fig. 43. — The anterior end, showing the corona and collarette. X 33- 



Fig. 44. — The anterior end, showing a rather longer corona, the abdominal ganglion, and the tactile 



prominences: of the latter only the larger were drawn. X 33- 



Fig. 45. — A jaw. • 43. 



Fig. 46. — The anterior teeth in place, slightly foreshortened. 210. 



Fig. 47. — The posterior teeth in place. 210. 



Fig. 48. — The corona ciliata with the externmost tooth. • 210. 



