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PROCEEDINGS OF THE 



[Dec, 1856. 



verging lines about the bulb are intended to represent the creases made in 

 the surface when it is thus pinched up by the tentaculum. 



PLATE 7. 



Fig. 31. — The stage subsequent to f. 28b — a. The proboscis shortened and the 



disk now developed. Seen in profile. 

 Fig. 32. — A view of the same from above. 



Fig. 32a. — The proboscis of the same becoming shorter and broader. 



Fig. 32b. — A view from above of the digestive cavity when the proboscidian ap- 

 pendage has entirely disappeared. The small opening in the centre is the 

 mouth. 



Fig. 31a. — Is a profile outline which I have observed the appendage to assume, 



when passing from form 32a to form 32b. 

 Fig. 32c. — The mouth of the larva about this stage, thrown into a quadriform 



shape. 



Fig. 33. — A profile view of the larva at the next stage of development — the pro- 

 boscis has disappeared. The tentacula 4 A- 4=8. This figure is not made 

 directly from nature since it was impossible to keep the delicate discoid em- 

 bryo in this position long enough to make the drawing. 



Fig. 33a. — A sketch of the larva at this stage, swimming freely in the water, made 

 with the aid of a pocket lens. It is swimming downward. 



Fig. 34. — A much magnified view of the larva from above — m, the gaping mouth; 

 s, the iEquorea-like stomach; b, the greater, and c, the alternate lesser ten- 

 tacula, all somewhat contracted ; g, the muscular areas ; t, the otolithic pen- 

 dents ; p, the small fleshy tubercle above ; v, the vail with its large cells 

 seen through the muscular areas ; x, the chord which stretches through the 

 muscular areas, from one tentaculum to another. 



Fig 35. — An enlarged view of the parts about the origin of the tentaculum — a, 

 the upward prolongation of the vail between the muscular areas, c, c; p, the 

 tentaculum; e, outline of its radix; d, tentaculum; b, outline of part of the 

 thickened perimeter of the digestive cavity formed by the junction of its 

 upper and lower walls. The lines across c, show the directions of the 

 several muscular constructions. 



Fig. 36. — Structure of a tentaculum and its attachment — d, tentaculum; e, radix, 

 showing the cells. 



Fig. 37. — Diagram, showing the direction of muscular constrictions ; z, concentric 

 constrictions ; y, radiate constrictions. 



Fig. 38. — Somewhat magnified otolithic cyst, and its attachment. 



Fig. 39. — Otolithic cyst, with two chrystals, the outline of one of which is more 

 clearly exhibited below. 



Fig. 39.— p. — Outline of the fleshy tubercle, showing several small round cells 

 which may be thread cells. 



Fig. 40. — The fleshy tubercle p, from a specimen decomposing, showing its struc- 

 ture and relations to the marginal thread, represented by the cellular tissue 

 below. 



Fig. 41. — p, another appearance of the same. 



Fig. 42.— Cells of the supposed nervous chord x, f, 34, stretching between the 

 tentacula, 



