ABYLA. 41 



hydroecium is a conical, wide-mouthed cavity, extending through less than half of the length 

 of the organ. The somatocyst arises from it by a short and narrow duct, which opens into a 

 large oval sac as wide as the nectosac, opposite whose extremity it suddenly contracts, and 

 sends off from its anterior wall a narrow, csecal process, which extends very nearly to 

 the upper edge of the nectocalyx. The walls of this organ are greatly vacuolated. 



The nectocalycine duct passes off at right angles from the base of the cocnosarc, and 

 divides opposite the middle of the nectosac. The distal nectocalyx is wider distally than 

 proximally. Its distal extremity is pentagonal, and of the five angles the four lateral are 

 prolonged into strong, serrated points (of which the left hand and anterior is the largest) ; 

 while the posterior is not at all produced, and as its ridge is correspondingly obsolete, while 

 those from the others are tolerably well marked, the organ appears to be only quadrilateral. 

 The posterior part of the proximal extremity is truncated, but anteriorly it sends off a short trian- 

 gular process, through which the nectocalycine duct passes. From the edges of the anterior 

 face two plates arise, which inclose the hydroccial canal (fig. 2 a). The wider, right-hand, plate 

 bends over, to end by a free, convex, serrated edge posteriorly, while its left, free edge is 

 smooth. It overlaps the other, which is narrower, rises perpendicularly from the anterior 

 surface of the organ, and ends in a number of very strong, distant, curved teeth. 



The hydrophyllia are subcubical, sending off a process from behind the middle of their 

 infei'ior surface. The phyllocyst has the form of a cross, with short, lateral arms. 



Length of the proximal nectocalyx . . f'j inch. 



„ distal „ 



„ hydrophyllium 



TB » 



1 

 Bo >' 



The history of my acquaintance with this species is somewhat instructive. On the 

 15th of April, 1847, while in the South Atlantic (lat. 38° 9' south, long. 52° 31' east), I first 

 made acquaintance with a detached proximal nectocalyx, with which only a single polypite 

 was connected, and which exhibited no trace of a distal nectocalyx. In the Indian Ocean, 

 off Timor, and in the South Pacific,^ I found other specimens in precisely the same condition ; 

 and it was not until the 22d of December, 1848, that I met with one having the small 

 inferior nectocalyx represented in fig. 2 c. The lower part of this organ had the form of 

 a pentagonal prism, with three strong posterior longitudinal crests, and two anterior ones. 

 All these terminated in strong incurved points below, and a strong plate projected backwards 

 internal to the right anterior ridge. The proximal moiety was an irregular pyramid, traversed 

 by the nectocalycine duct, which connected its extremity with the ccenosarc. This organ 

 was so small as not to project beyond the hydroecium. 



This specimen, like the others, had only one polypite, and on subsequent occasions I 

 repeatedly took the animal in the same state, and without any sign of a distal nectocalyx ; 

 until, at last, on the 2 1st of July, 1849, while off the south-east coast of New Guinea, I 

 obtained the entire individual represented in fig. 2. Even in this, however, the ccenosarc 



' Leuckart (Z. U., p. 41) remarks on the wide geographical distrihution of Ahijla penlajona. 

 Quoy and Gaimard took it at Gibraltar, and " in different seas" (' Zool. de I'Astrolabc,' iv, p. 90) ; 

 Delia Chiaje and Costa at Naples ; Kolliker at Messina. 



6 



