26 THE CRAG POLYZOA. 



Genus 2. ALYSIDOTA, Busk. 



Cellulis urceolatis, uniserialibus ; ramis cellulae summitate surgentibus. 

 Cells urceolate, uniserial ; branches springing from the summit of a cell. 



ALYSIDOTA, Busk, Quart. Jour. Mic. Sc., iv, p. 31 1. 



In the British Museum Catalogue of Marine Polyzoa, p. 82, pi. xcii, figs. 1, 2, a 

 species of Lepralia is described and figured under the name of C. labrosa, in which the 

 series of cells are not contiguous as in a true Lepralia, but divergent, branching out 

 irregularly from a common point, around which the cells are sometimes crowded together 

 without any definite order. Standing alone as it then appeared to do, this species 

 was regarded as an aberrant Lepralia, a genus to which the present is undoubtedly 

 very closely allied. But when a second well-marked form of the same kind was 

 noticed by Mr. Alder, it seemed advisable that similar growths should be associated into 

 a distinct generic group. The latter species, of which numerous specimens have since 

 been collected by Mr. Barlee in the Orkneys, will be found described in the ' Quart. 

 Journ. Micros. Sc./ p. 311, and figured in pi. ix (Zoophytology), figs. 6, 7. 



The genus stands between Hippotliou and Lepralia, though perhaps more closely 

 allied to the latter than to the former, from which it is distinguished by the circumstance 

 that the cells arise from each other by a broad base, or are, as it were, immediately con- 

 tiguous without the intervention of a tubular prolongation, and that the branches divide 

 for the most part dichotomously or irregularly, while in Hippothoa, owing to their always 

 springing in opposite pairs from the sides of a cell, from which a third series is also con- 

 tinued in the original direction, the ramification may be termed trichotomous. 



1. A. LABROSA, E. PI. XXII, fig. 7. 



Cellulis ovatis puncturatis ; orificio orbiculari, peristomate valde elevato, incrassato, 

 expanso, supra ssepius einarginato ; ovicellula globosa, glabra, recumbente. 



Cells ovate punctured ; orifice orbicular, with a much-raised, thick, expanded peristome, 

 which is often deficient above or behind ; ovicell globose, smooth, recumbent. 



LEP. LABEOSA, B., B. M. Cat, p. ii, p. 82, pi. xcii, figs. 1, 2. 



Habitat. Red Crag, on inside of a shell, S. W. (Recent) ; Belfast Bay, in deep 

 water, on the inside of a dead shell, W. Thompson. 



