76 



EUCHEILOTA DUODECIMALIS. 



FiR. 107. edge ; in the cavity hangs a short urn-shaped digestive sac, 

 attached to the four chymiferous tubes by a circular base, 

 aud not quadrangular, as in the E. ventricularis ; there is 

 only a single granule in each of the marginal capsules. 

 This sjjecies seems to be full grown, as the sexual glands 

 were very much distended with spermaries, and I could 

 not see any traces of additional tentacles ; however, as 

 the presence of eggs and spermaries is far from being a 

 criterion of maturity among these animals, we must have 

 further materials to decide this point. Only three speci- 

 mens of this species were found, — a very young female, 

 the male here figured, and an older female (Fig. 107''), in 

 which the ovaries were filled with apparently mature eggs, 

 the genital pouches extending from the base of the chymif- 

 erous tubes to the base of the j)roboscis ; the thickness of the 

 bell and its shape is totally different from that of the male, if it belongs 

 to the same species ; the bell is of uniform thickness, quite squarish 

 in outline ; the trace of the connection with the Hydrarium is still 

 very distinct, and the tentacles are cari'ied in the erect manner so 

 characteristic of young Hydroid Medusae, showing that, in spite of its 

 weU-developed ovaries, it must have but recently been liberated from its 

 p.^ jjj^ Hydrarium. The character of the differ- 



ence between the young of these two sj)e- 

 cies of Eucheilota makes it highly probable 

 that the M duodecimalis may form, when 

 its adult is known, the basis for a separate 

 genus ; we find in the arrangement of the 

 capsules differences similar m character to 

 those observed between the young of Oce- 

 ania and of Clytia, the adult Medusae of which are generically distinct, 

 I cannot help surmising that we shall find differences of a like nature 

 when the adult of E. duodecimalis becomes known. This is the more 

 probable now that we know the young of E. ventricidaris, the adult 

 of which has so much the general a^jpearance of an Oceania. 

 Buzzard's Bay, Naushon (A. Agassiz). 

 Cat. No. 453, Naushon, July, 1864, A. Agassiz. Medusa. 



Fig. 107. Junction of one of the chymiferous tubes ivitli the circular tube, o, spermary ; c, 

 marginal capsule ; t, one of the four primary tentacles ; t', tentacular cirri. 

 Fig. 107". Female Medusa of Eucheilota duodecimalis ; greatly magnified. 



