56 F. A. SMITT, 



ter, indeed, of E. pertusa, as quoted by the first-named author, is of no constant 

 value, because in a colony, which was taken by Pourtales at the same locality with 

 the preceding species, sorae of the zooecia are plain, other ventricose, presenting all 

 the characters of E. pertusa. But here it is of the greatest interest, on some of the 

 zooecia, at the articulation of the operculum in the zooecial aperture, to find a little 

 lateral denticle, corresponding, evidently, to the above-described on the E. sanguinea, 

 although considerably smaller. When this is formed, as the proximal margin may be 

 sharpened, internally, by a concave rim, in this species we meet again the Gemellipo- 

 ridan character of the zooecial aperture, although not fully typical. Furthermore, its 

 constitution, in other points, bears a very close resemblance to the above-described 

 Gemellipora lata. The pores in the zooecial wall are greater and more numerous, and 

 instead of the depression proximally of the zooecial aperture, here we find tubercles; 

 these are the most pregnant differences in the zooecial construction, of no great value, 

 certainly, as being only variations of the calcification. The avicularia of the Gemelli- 

 pora. lata, also, have their correspondence in the E. pertusa, as well as in the greater 

 ones of E. sanguinea; for, although here, generally, they seem to be wanting, on the 

 older part of the colony, in the same position as that described above on Gemellipora 

 lata, I find two decumbent avicularia, of a lengthened shape, about two thirds the 

 length of the zooecia. Their sides are swollen. The opercular apparatus is worn away, 

 but the groove for the mandible indicates an acute form of it. 



Thus, the Escharella pertusa seems to hold an intermediate position between the 

 Gemellipora lata and E. sanguinea, closely related to them both. What we mean by 

 placing these forms in two different subgenera, may be understood from our remarks 

 before. Wherever, in this very natural group, we have sought for any generical di- 

 stinctiveness, in one or another way we have seen it to be faded away. 



At the side of the Escharella pertusa, and, indeed, very difficult characteristically 

 to distinguish from it, is to be placed, also, the 



Escharella Audouinii 1 ) (Pl. XI, fig. 211). 



The most applicable character, for the distinction from the preceding species, 

 will be the size of the zooecia, the inner breadth of their apertures here amounting to 

 about 0,23 mm., in the same ti me as the thickening of the börder of this aperture is 

 more advanced, so that the outer breadth of the raised secondary aperture amounts to 

 about 0,33 mm. The worthiest character, on the contrary, from systematical point of 

 view, is the difference in shape of this aperture, which here is contracted in the 

 middle, at the articulation of the operculum. The variations in the convexity of the 

 zooecial front-wall are almost the same as in the preceding species, although here, usu- 



x ) (?) Flustra torqnata, Lmrx. in Quoy et Gaim. Voy. de VUranie, Zool., p. 610, tab. 89 figg. 7 et 8; 

 M. Edw. (Escharina) in Lam., Anim. s. Vert, ed. 2, vol. 2 p. 234; D'Orb. (Cellepora) Pal. Franc 

 Terr. Gret., vol, V p. 403. 

 Cellepora Manynevillana, Aud. in Sav. Descr. d. VEgypte, Polypes, tab. 8 fig. 6; D'Orb. (Cellepora Au- 

 douinii) Pal. Franc. 1. c. p. 401. 

 (?) Cellepora ovoidea Id., ibid., fig. 1; D'Orb. (Cellepora subovoidea) Pal. Franc, 1. c. p. 402. 



