28 G. HERBERT FOWLER. 



iv. Memoirs referring to the Genus : — 

 Milne-Edwards and Haime, "Hist. Nat. Corall.," iii., p. 311, 



pi. f 4, fig. 3. 

 Klitnzinger, " Korallthiere des Eothen Meeres," ii., 69, pis. vii., 



viii. 

 Agassiz, "Nat. Hist. United States," iv., p. 296, pi. xv., fig. 15. 



POCILLOPORA BREVICORNIS (Figs. 14, 15). 



The anatomy of this species agrees so closely with that of 

 Seriatopora subulata that only points of difference between the two 

 need be quoted. 



The corallum is, of course, different in its mode of growth, as upon 

 this the distinction between the two genera is based, but this differ- 

 ence does not affect the anatomical relations of the polyps. The 

 method of support of the external body wall is identical with that in 

 Seriatopora ; the tentacles agree in the two forms, though, as they 

 are fairly well expanded in my specimens, it does not appear whether 

 they are capable of introversion or not ■ the stomatodseum is less 

 distinctly conical than in the cognate genus. 



As regards the mesenteries, the only points of difference noticeable 

 are, that in Pocillopora those denoted in the diagram (Fig. 9) by the 

 numbers 3, 10, are not proportionately so much longer than those 

 marked 1, 5, 8, 12, and that a mesenterial filament may sometimes 

 be detected on the four last mentioned ; in other words, the tendency 

 observed in both Seriatopora and Madr. Durvillei towards the exclusive 

 assumption of function on the part of six mesenteries and towards a 

 correlated retrogression (?) on the part of the other six, has not attained to 

 such a pitch in Pocillopora (and Madr. aspera) as in the other two forms. 



The statement of Professor Moseley (10), that " the mesenterial 

 filaments are not enclosed in prolongations of the chamber walls," is 

 not justified by the examination of sections; the two longer and 

 more developed mesenteries, with their filaments, 3, 10, lie, as in 

 Seriatopora, for their whole length in the ccelenteron. 



Apparently, any of the mesenteries may bear generative organs, 

 and it is worthy of remark that the polyps are moncecious. The 

 ovaries and testes, though surrounded by a thin capsule of mesogloea 

 and endoderm, as in typical forms, do not lie, as is generally the case, 

 in the plane of the mesenteries (cf. Fig. 3), but project from their 



