DIPHYES. 35 



off obliquely from behind downwards and forwards. The hydroecium is very short, not 

 equalling more than a fourth the length of the whole organ, and its apex is curved backwards, 

 so that its contour resembles that of a Plirygian cap. The somatocyst is connected with 

 its anterior face, below its apex, by a narrow duct, and then expands into a wide subcylindrical 

 sac, which terminates superiorly at about the junction of the inferior and middle fourths of 

 the length of the organ. The nectosac gradually widens from its mouth, and having attained 

 about two thirds of its entire length, gradually narrows again to end in a rounded apex, 

 close to the superior extremity of the organ. 



The distal nectocalyx is hardly more than two thirds as large as the proximal. The 

 nectosac occupies not more than two thirds of its length. It is elongated, wider in the 

 middle than at the ends, and is rounded superiorly. The inferior aperture is situated in the 

 middle of a truncated facet, with almost obsolete ridge points, as in the proximal necto- 

 calyx. 



The distal portion of the organ, which contains the nectosac, is obliquely truncated 

 proximally, passing into a slender beak-like process of the proximal moiety, which is inserted 

 into the liydroecium of the proximal nectocalyx, and carries the nectocalycine duct. 



Two perpendicular plates rise from this process, and run down parallel with one another, 

 to end below in free, pointed and serrated processes, which extend far beyond the aperture 

 of the nectosac, and whose posterior edges are united for about half their length by a trans- 

 verse plate (fig. 2 3). This continues downwards the floor of the hydrcecial canal, which is 

 bounded at the sides by the two perpendicular plates, and in part by a transverse lamina, 

 which stretches from one plate to the other for the greater part of their length. 



The hydrophyllia are like those of Biphyes dispar, but are without the inferior truncated 

 edge and acuminated angles.' 



Length of the proximal nectocalyx . . i| inch. 



Depth „ „ . • n „ 



Length of the distal nectocalyx . • W „ 



Depth „ „ . • - i's „ 



This species was particularly abundant in Bass s Straits, in February, 1848. Several 

 specimens were also taken in the southern part of the Indian Ocean. It has been taken^ on 

 the Irish Coast, and it seems to abound in the Mediterranean. Leuckart says he has seen it 

 with a hydrosoma many inches long when fully extended, and with as many as fifty 

 completely-developed polypites. 



I entertain no doubt tliat the species which I have here described is identical not only 

 with the D. appendictdata of Eschscholz, but with the B. Sieboldii of Kolliker. Leuckart 

 admits that the D. gracilis of Gegenbaur is the same as Kolliker's D. Sieboldii. And in this I 

 fully agree with him, though Gegenbaur says that the hydroecium of the distal nectocalyx 



' Compare Leuckart's account of their structure, Z. U., p. 67. 



' See a ' Note on the occurrence of the genus Diphya on the Coast of Ireland,' by Air. G. C. 

 Hyndmau ('Annals of Natural History,' vii, 1841.) Mr. Hyndman names the species D. ehngata, 

 but from his sketches I entertain no doubt that it is D. appendiculata. 



