42 E. A. SMITT, 



ding concavity of the proximal margin and the same three sinuses. These then are 

 of almost the same size, but by little and little, as the concavity of the proximal mar- 

 gin, by the proceeding calcification, is filled up, the median sinus grows deeper, until 

 the Hippothoan form of the aperture is finished, although the lateral sinuses, reminding 

 of the Gemelliporidan state, never seem to be obliterated. 



The greatest breadth of the zooecial aperture I have measured to be about 0,u mm. 



For the most typical Hippothoan form of the zooecial aperture, we may cite the 



Hippothoa spongites J ) (Pl. VIII, tigs. 161 — 163). 



This, as an American species, in all probability, was already known by Pallas, 

 although that author, even as the most of the ancient writers on this subject, in de- 

 termining it after the form of the colonial growth seems to have conjoined it with the 

 other escharines, which grow in the more or less complicated Hemescharan (auctt.) manner. 

 The only one, before Busk, who evidently gives the true character, is Moll. At the 

 side of the typical form, a great group of varieties is to be placed, which very ea"sily 

 may be clefined as distinct species, in the same manner as one might do it with the 

 varieties of Porellina ciliata. Such a variety, characterized by the transformation of 

 the avicularia into vibracularia, under the name of Eschara vulgaris, var. a, was already 

 described by Moll, and, in a harder degree of calcification, closing the primary pores 

 in the front of the zooecia, under the name of Lepralia vulgaris, from Madeiran speci- 

 mens it was described by Busk (Quart. Journ. Micr. Se, vol. VI, p. 127, Zooph., tab. 

 XVIII, fig. 3) and, from Adriatic specimens, under the name of Lepralia Stossici, it 

 seems also to have been described by Heller (1. c). In my papers on the Scandi- 

 navian and Arctic Bryozoa, proceeding from that form as the starting-point for the 

 comparison, under the collective name of Mollia vulgaris, I have discussed the relations 

 existing between the valnations of this type, as occurring in the northern seas. 



In the southern regions, the Hemescharan growth, which was thought to be the 

 medicinal Adarce of the ancients, seems to attain its greatest development and to be 

 the most usual colonial form of the Hippothoa spongites. Such it was taken by Poue- 

 tales, in fragments of a contorted, tubular construetion, from the depth of 35 fathoms. 

 Together with these, as well as higher up in the sea, from the depth of 13 fathoms, 

 he took also its Lepralian (auctt.) growth. 



The rectangular zooecia, with their almost plain front-side pierced by pores and 

 limited by a raised ridge, the semicircular zooecial aperture, with a breadth of about 

 0,1 mm. and with its median sinus proximally a little dilated, the acute, lateral avicu- 

 laria, with a breadth at the articulation of the mandible of about haif the breadth of 



] ) Eschara spongites, Pall., El. Zooph., p. 45; Espek (Gellepora) Pflanzentli., vol. 1, p. 242, Tab. Cellep. 

 III; Moll (Eschara) Esch. p. 34, tab. 1, figg. 3, A et 3, B; — (de veteribus synonymis, quoad certa 

 esse possunt, vide hos scriptores!) — ; Lmrx. p. p. (Gellepora) Expos. Méth., p. 2, tab.' 41, fig. 3; Lamk. 

 p. p., Anira. s. Vert., ed. 1, vol. 2, p. 176; ed. 2, vol. 2, p. 258; Blnvlle, p. p. (Eschara) ActinoL, p. 

 429 (Diet., tomi LX p. 394). 



Lepralia spinifera, p. p. Busk, Cat. Polyz. Brit. Mus., tab. XCI, figg. 1 et 2. 



Lepralia serialis, Helleii, Verb. k. k. zool. bot. Gesellseh., Wien 1867, Bd. XVII, p. 104. 



Lepralia spongites, Heller., ibid. 



