MUSEUM OF COMPAEATIVE ZOOLOGY. 283 



and not a tnbe, and is strictly homologous to a like structure in Cunina dis- 

 coides, Fewkes. It lies on the outer surface of the bell, while the radial tube 

 follows the inner or the bounding wall of the bell cavity. There are four 

 otocysts, each closely resembling the otocyst of the adiilt in the larval form 

 which has just been described. Each otocyst is placed on the bell margin at 

 the point of attachment of the solid tentacle. 



The next oldest larva to that already described is one which, together with 

 the following (figs. 3, 4), may be referred to the ^^ fifth period " (Haeckel) of 

 G. eurybia. It corresponds in some respects with fig. 20 in Fritz Miiller's 

 account. In this larval stage (fig. 3) the most marked addition to the former 

 is the growth of tentacular bodies on the bell margin midway between the solid 

 tentacles (c). They lie near the union of the radial vessels with the circular 

 tube, and are the beginnings of the long flexible tentacles. They are in a larva 

 even as young as fig. 3 banded with the lasso-cells characteristic of the adult, 

 which seems to be true in a larva of the same age figured by Haeckel (PI. III. 

 fig. 37). Fritz Miiller represents two of these appendages as formed prior to 

 the remainder. The stage of such a larva may be a little younger than my 

 fig. 3, in which all these bodies, four in number, were equally developed. The 

 most important difference between the two figures (figs. 3, 4) which are given 

 to represent the fifth period is the result of the growth of the proboscis, which 

 even in this larva is ditferentiated into a basal peduncle and a terminal stomach. 

 The larva has still only four otocysts. 



Haeckel's account of the development of G. eurybia closes with the fifth 

 period. Between that and the adult he has gi^en no figures of intermediate 

 stages. Fritz Miiller's paper, however, has one more stage intermediate be- 

 tween these two, in which there appear to be ten otocysts on the bell margin 

 intermediate between the radial canals, before the organs corresponding to the 

 tentacles («) are dropped. In the present species the otocysts of the long 

 tentacles do not' develop before the complete loss of the bodies (c). 



Fig. 5 represents a larva in the sixth period of its development. This larva 

 differs from that last represented (fig. 4) in the growth of the long tentacle on 

 the bell margin and the total loss of the tentacle (a). It is to be noticed, 

 however, that there are still but four otocysts, and that these bodies lie at the 

 bases of the solid marginal tentacles (c). A larva still older than this, but 

 undoubtedly to be placed in the same period {sixth period) is the first in the 

 series having eight otocysts. The four sense bodies additional to those at the 

 base of the marginal solid tentacles appear at the base of the long tentacles 

 for the first time in a larva represented in fig. 6. This larva has assumed the 

 form of the adult in many particulars, one of the most prominent of which is 

 the enormous development of the proboscis. The sexual glands have not yet 

 begun to form, or at least are not represented. In a larval form which ap- 

 proaches very closely the adult, the sexual glands are well developed and 

 crowded with ova. Such a larva is figured in fig. 7, which represents the 

 Glossocodon as seen from the aboral pole. In the adult the only representative 



