THEONOIDiE. 129 



Genus 15. Fascicularia, Milne- Edwards. 



Polyzoario raassivo globoso sessili, e fasciculis cellularmn j)roi'sus coaiitaniiu ct c basis 

 centre ad periplieriara undequaque radiaiitibus composito. 



Polyzoariura globose, massive; constituted of distinct bundles of contiguous tubes; the 

 bundles radiating from the centre of the base, in all directions, towards the periphery. 



Fasciculauia, Milne-Edwards, 1836 {M.S.) ; Lyell ; S. Wood, 



Theonoa (sp.), .S. Wood ; (sp.) Auct. 1 



Meanuripora, ly Orh'tymj. 



Apsendesia (pars), Blainville ; Lamx. (?). 



This genus, which, though named, does not appear hitherto to have been fully 

 described, may be regarded at present as quite peculiar to the Crag, and in all probability 

 to the Coralline Crag-, for though found in the Red Crao; there can be little doubt, as 

 observed by Mr. S. Wood, that these stray specimens have been introduced from the 

 underlying coralline beds. 



The pe3uliarity of the structure of the polyzoarium consists in its being made up of 

 radiating bundles of tubes, which bundles, in one of the two species, are cylindrical, and 

 of pretty nearly uniform dimensions throughout, whilst in the other they are more irre- 

 gular in size and form. A striking distinction, also, is observable in the mutual relation 

 of the bundles of tubes to each other in the two species. In one, the cylindrical bundles 

 are nnited, at regular distances apart, by what may be termed tabular, hoi'izontal septa, 

 indicating probably periodical lines of growth, and which lines are thus concentric to one 

 another. In the other species the bundles of tubes anastomose more irregularly, 

 approaching each other and coalescing for some distance, and then separating again. In 

 consequence of which the appearance of periodical lines of growth, though obvious enough, 

 is not so distinct as in the other species, and the aspect of the surface is also rendered 

 widely different, which presents in the one case rounded eminences, on which the tubes 

 open, and in the other undulating anastomosing riclges. 



The only genera with which the present can be confounded, are Apsendesia and 

 TJieonoa of Lamouroux. With respect to the former, as defined by that author himself, 

 there seems, upon reference to his description and figure^ of the typical species J. crislata, 

 — " subglobosa vel hemispheric;a ; laminis exsertis, rectis, diverse convolutis, uno latere 

 lamelliferis" — to be no reason whatever to regard it as in any way allied to Fascicularia. 

 except in outward configuration ; nor, in fact, is it certain that it is a Polyzoon at all. It 

 is otherwise, however, with the genus as defined by M. de Blainville,^ who, as it would 



' 'Exp. Meth.,' p. 81, pi. Ixxx, figs. 12—14. 

 2 ' Man. d'Actiii.,' p. 408. 



17 



