Stephknson — The Genus Cnrallimorphus. 183 



possesses very largo neniatocysts. One of these, taken from the body-wall 

 ectoderm, is figured in PI. XX, fig. 3. It is not very clear, because it was 

 surrounded by other cells in a section, but will serve to show the size and 

 general appearance. Its outline was traced with a camera lucida under 

 oc. 3 and a -j-V oil-immersion lens, and the size therefore is accurate. 



General coiisiderations. — Three species of Corcdlimorphvs have been 

 described by Moseley and Hertwig, not very different from each other. 

 These Irish specimens are not quite like either, but are nearest to C. rigidus. 

 The question arises : are the three species really distinct (for, if so, the Irish 

 form would probably require a fourth), or do they all belong to one variable 

 species ? We only know the entire genus from partial descriptions of a 

 limited number of specimens, of which hardly two are quite alike. One 

 criterion of separation used by Hertwig is that in C. riyidus the furrows on 

 tlie body-wall correspond to mesenterial insertions ; and in C. oUcctvs they 

 correspond, at any rate in part of the body, to the middles of the exocoels 

 and endocoels. This seems a trivial feature, and one liable to individual 

 freaks of growth of the mesogloea. When we come to tlie tentacular arrange- 

 ment, we find tliat the distinction of C. profundus is that its disc-tentacles 

 do not exceed 12 or 13 in number, however large it gets, whereas in 

 the others there are more, up to 31. This may be a valid distinction, 

 but would require a laiger amount of material for verification. As a 

 matter of fact, the arrangement of the tentacles varies a good deal, and forms 

 a sort of series in the genus, as the accompanying table will show. It may 

 be noted that the number of marginal tentacles runs from 42-48 in the 

 rUjidns and ohkctus of Moseley and Hertwig, 48-52 in ■profundus, and 60-68 

 in the Irish form. Again, the disc-tentacles in Hertwig's and Moseley 's 

 rigidus and oUcdus run 12 (young specimen), 20, 22, 24 in difVerent 

 specimens. \\\ 2wofund%ts there are 12 or 13; in the Irish 21-31. It 

 is worth noting also that in tlic small specimen referred to in tlie table 

 as rifjidus 1, and whicli Hertwig assumed to be young, the full number 

 of marginal tentacles was present, although only 12 discals. The Irish 

 specimens are quite distinct in one way — the number of secondary marginal 

 tentacles is 14-15, whereas the other forms have only G-7 of them ; and 

 there are corresponding changes of number in the 3rd and 4th cycles. Again, 

 although one Irisli specimen is much smaller than the other, it has nearly as 

 many tentacles — a fact which points to its being adult, but poorly nourished. 

 A point Hertwig mentions is the relative diameters of oral and pedal discs. 

 This is not valuable here as a specific character — the two Irish specimens, 

 obviously the same species, diller in this respect. C. ohtcdus had 24 pairs of 



