30 F. A. SMITT, 



is the rest of the proximal avicularium. Usually between these, then, a transverse 

 furrow is to be seen över the middle of those zocecia. 



As in the preceding species, avicularia of a greater size but of the typical form 

 here, also, sometimes are developed in the margin of the branches. In the Australian 

 form they seem to corresponcl with those figured b}- Milne — Edwards ')» as placed 

 between the zooecia. 



In this species, already, we see the Porinidan type, in its zocecial conformation, 

 very much approaching that type, which, after D'Orbigny, I have proposed to be named 

 Escharella. I need only to refer to a comparison between this and the zocecial con- 

 formation of the Escharella palmata. The same likeness with the Escharella?, in their 

 hardest calcification, we find in the 



Porina violacea 2 ) 



of what species Pourtales sent me one fragment of a colony, growing on a Nullipora, 

 taken from the depth of 35 fathoms, W. off Tortugas. 



Its colour is that peculiar black purplish-Mue tint, which is so well known from 

 European specimens. The zocecia, in their härd calcification, are very much thickened, 

 warty on their glossy surface. From the deeply immersed median pore in the middle 

 of the front-side, the avicularium, with its pointed tip, points directly distally up to- 

 wards the middle of the proximal margin of the zocecial aperture, whose breadth I 

 have measured to about 0,09 mm. 



With reference to the fine distinction, at first pointed out by Busk, between the 

 Porina violacea and the 



Porina jjlagiopora 3 ) (Pl. VI, tigs. 134 and 135), 



which both forms lived together in the Crag-period, we have here to register the last- 

 named form, also, among the living Porince, in very well developed colonies, encrusting 

 shells and Nulliporae, taken by Pourtales at a depth of 60 fathoms, West off Tortugas. 



Its colour is almost the same as that of the preceding form, but a little lighter, 

 purplish-blue. 



Besides the oblique direction of the avicularium and its greater size, already 

 pointed out by Busk, it differs from the P. violacea, particularly, through the size, also 

 of the zocecial aperture, whose breadth I, here, have measured to about 0,14 mm. 



Otherwise, these two Porince so closely agree with each other, that I think we 

 have reason to regard the P. -plagiojpora as a variety of greater development of the 

 same specifical type as the P. violacea. For, with a greater development of the avi- 

 cularium (what very often is to be observed within the limits of the bryozoan species) 

 this probably, for finding place enough, would turn itself obliquely. 



>) 1. c, pl. V, fig, 2 at d. 



2 ) Lepralia violacea, Johnst., Brit. Zooph., ed. 2, p. 325, tab. LVII, fig. 9; Gray {Escharella) Brit. Mus. 

 Cat., part. I (Rad.), p. 125; Busk (Lepralia) Gat. Brit. Mus., Polyz,, . p, 69, tab. LXXXVII, figg. 1 et 2; 

 Id., Grag Polyzoa, p. 43. tab. IV, fig. 3. 



3 ) Lepralia plagiopora, Busk, Grag Polyzoa, p. 44, tab. IV, fig. 5. 



