28 E]\LBRYOLOGICAL MONOGRAPHS. 



IS, 19. Agalma Sarsii. From MctsclmikofT, op. cit., PI. IX. figs. 15, 17. 



18. Larva, showing the connection of the embryonic appendages (primitive hydrophyllium and serrated liydro- 



phyllia) witli the polypite and pneumatocyst {pn cy. ), by means of an axis (;3). Four seiTated liydropliyllia 

 are shown. The connection of the cavity C. P. L. with that of the jiolypite is through an enhirgement 

 (ampulla a), into wliich the tubes of the several liydropliyllia appear also to open. Tlie cluster of bodies 

 at the base of the jiolypite, near its junction with tlie pneumatocyst, are embryonic tentacular knobs 

 (figs. 23, 24). ga. Stomach cavity, or. Moutli. 



19. Larva about the same age as the last, turned in such a way that a serrated liydropliyllium is shown in full 



face. Tlie fore-shortened e.xtiemity of tlie tube (C. P. L.) of the iiriniitive liydropliyllium is just visible. 

 jir. liijph. Pi'imitive hydiophyllium. pig. Pigment at the base of the float [pii ph.). ga. Stomach. 

 nt cij. Nematocyst. 7. Tube of the serrated hydrophyllium. 



20. Agahna ehgans. From Fewkes, Studies of the Jelly-fishes of Narragansett Bay. Bull. Mas. Com}}. Zoiil., 



Vol. VIIL, No. 8, PI. LX. fig. 2. 

 " Allwrybia larva," embryo with a ring of provisional serrated hydrojihyllia (.«<-»■. hiiph.), and cnibiyoiiic 

 tentacle (cm. ta.), with a provisional (?) a.\is. There is a remnant of a vitelhis {vt.) which, in this sjiecics, 

 does not pass into the polyiiite. Our species of Agnlvia seems to resemble Cn/stallodcs in its methoil of 

 absorption of the vitelhis. The pneumatophore {pnph.) is permanent. 2>l/^- Polypite. 7. Median canal 

 of the serrati'd liydropliyllium. 



21. From Metsihnikofl', op. cit., PI. XL fig. 2. 



An embryo older than the " Alhoryhia larva," with the serrated liydropliyllia characteristic of that stage, 

 and with embryonic tentacle (cm. la.). It has developed two nectocalyces at least (lica-.), a permanent 

 axis (ax. ), permanent tentacular knobs, two of which are to be seen in the lower centre of the figure just 

 above the letters (cm. la.). A radial tube. (1: lb.) is developed in the tentacle, and the piieumatopliore 

 (pnph.) approximates in shape that of the adult. 



22-29. From Fewkes, op. cit., PI. IX. figs. 1, 9, 9". Fig. 25, from sketch. 



22. Larva still retaining, as an embryonic feature, the provisional tentacle and knob ; but in other respects like 



the adult. Provisional hydropliyllia lost, and in their place jiermanent covering-scales (hydroiihyllia). 

 Axis divided into two parts; that which bears the nectocalyx (nc.s.), called the nectosteni, and that 

 which bears tlie reiiiaiiiing appendages, the polyp stem (pg. s.). The pennanent tentacle, with knobs 

 characteristic of the genus Agahna, coexists with the larval tentacle (cm. ta.). Hydrocysts (hi/cy.), with 

 their filameuts (Jil. hy cy. ) present, nc x'. Rudiinentary nectocalyces. 7;)t j)/i. Pneumatophore. 2'U^- -^ 

 polypite. 



23-24. Embryonic tentacular knob of Agahna clcgans. 



23. Side view. 



24. Seen from below. 



25. Outline of an undeveloped hydrophyllium, not serrated, found in a larval Agahna clcgans. a. Anterior 



(place of attachment). j>- Opposite end. v. Ventral (side turned to the axis). 

 26-29. Development of the tentacular kiiol) of Physophora hydroslat ica. From Fewkes, Contributions to a 

 Knowledge of the Tubular Jelly-fishes. Bull. Mus. Comp. Zoiil., Vol. VI. No. 7, PI. I. figs. 4, 5, 6, 7. 



26. 27. Young condition of the knob. t. vx. Embryonic vesicle, resembling the terminal vesicle of the adult knob 



in Agahna. This is reduced in size, and lost in the adult Phyiophora. 0. Enlargement of tlie cavity of 

 the knob, which later grows into a canal {en.) along the side of the coiled part of the adult kiioli. 

 X. Point of origin of the coiled part of the knob. 



28. In tliis figure the vesicle (t. vs.), formerly terminal, has become lateral (I. vs.), and the cavity (0) has been 



elongited into a canal (en.) by the growth of the point of attachment of the coiled part of the knob to the 

 pole opiiosite its peduncle, or attachment to the tentacle, iv. Involucrum. sac. Sacculus. 



29. Kiiol) similar to that of the adult. Tlie lateral (embryonic) vesicle is lost, the canal (en.) tube-like, and the 



attachment (\) of the sacculus to the inner wall of the involucrum at the opposite pole to that where it 

 formerly hung. 



