HALOPSIS. 99 



dovolopment ; they are not capable of great expansion, and when short- 

 ened, the extreiiiities are curled up. The ovaries, which are linear, 

 extend along the chyniiferous tubes in such a way as to leave both the 

 actinal and abactinal extremities free (Fig. 142) ; the spherosonie in- 

 creases very gradually in thickness from the circular tube towards the 

 abactinal pole. This species differs (.,„ j^., 



from the S. lentkidare of the Falk- 

 land Islands, in having a smaller 

 free area, longer chymiferous tubes, 

 and more nuuierous tentacles ; it 

 grows from one and a half to two 

 inches in diameter, and half an inch 

 in height, is sluggish in its movements, is colorless, and has a gelatinous 

 disk of considcral)le consistency. These Medusa? are frequently found 

 thrown up on the sandy beaches, encased in sand in such a way as to 

 be preserved from decomposition and loss of shape for several days. 

 This may explain the mode in which the few fossil Medusoe known 

 have been formed. 



Massachusetts Bay, Nahant (L. Agassiz). 



HALOPSIS A. Agass. 



Halopsis A. Agass. ; in Proc. Bost. Soc. Nat Hist., IX. p. 219. 18G3. 



The genera Berenix and Carisochroma have been placed by Professor 

 Agassiz among the Williadre on account of their forking chymiferous 

 tubes. The discovery of Ilalopsis shows this association to be \\\\- 

 natural, and that most probably, when the genera Berenix and Cariso- 

 chroma are better known, they will be associated with Ilalopsis into a 

 distinct family, the Berinicida) of Eschscholtz. Whatever may be the 

 result, it is at least highly probable that tlicir closer relations are with 

 the ^Equoridte, and not with the Tuljulariau family of the Williada). 



Halopsis ocellata A. Arass. 



Ilalripxis ocellata A. A(iAs.s. ; in Proc. Bost. Soc. Nat. Hist., IX. p. 219. 18G3. 



The genus Ilalopsis differs from the other yEquorida? by the presence 

 of large compound e^'cs, as in Tiaropsis, from three to six between 

 every two of the chymiferous tubes. There are likewise long tentacu- 

 lar cirri ; the Hatness of the disk, the large number of tentacles, the 

 nature of the digestive cavity and of the genital organs, place this 

 genus among the iE(iuorida). Two species are found on our coast. 



Fig. 112. Till' sanii! as Fig. Ill, solmi in profile. 



