303 Bibliographical Notices. 



each after its kind. We have the early stages of one or two species 

 distinctly traced ; and there is a very good account of their ciliated 

 ova. 



The chapter is illustrated with eight plates, representing Flustra 

 carbasea, foliacea and truncata. The Fl. papyracea represented in 

 plate 7 is very unlike any specimen of the species we have seen, and 

 we are inclined to think it no other than a variety of Fl. foliacea. 

 Plate 8 represents not solely Flustra Murrayana, but, as we would 

 conjecture, three species; viz. fig. 1. Cellularia avicularia ; fig. 2. pro- 

 bably Flustra Murrayana ; and fig. 6. certainly Flustra avicularis. 



Chapter 2 treats of " Investing Ascidian Zoophytes," and has 

 three illustrative plates. The first of them (pi. 9) represents Flustra 

 hispida remarkably well ; and the species is well described in the 

 letter-press. The polype has about thirty-five tentacula. " None 

 of the marine ascidian hydrae have shown me a complement alike 

 numerous. This animal is likewise among the larger species, being 

 about a line and a half in height, and the tentacula composing its 

 cell expanding nearly as much. Its form is elegant, light and beau- 

 tiful. It rises very leisurely and gradually from the cell ; but its 

 retreat is most precipitate, vanishing in a moment." (p. 30.) The 

 ovum has the same origin and properties as that of Flustrce gene- 

 rally, but it is quite different in shape from any of them : it is " pure 

 white, elliptical, thin, and fringed by a border of active cilia, — all 

 which renders it a beautiful object under the microscope." This 

 peculiar figure of the ovum, taken in conjunction with the peculiar 

 substance of the polypidom, would vindicate the claim of the pro- 

 duction to be the type of a new genus. 



Alcyonidium parasiticum (pi. lOJ is equally well figured and de- 

 scribed. Plate 1 1 illustrates a new species named Alcyonidium my- 

 tili, from its infesting chiefly the shells of the mussel. The species 

 w^ould have been better placed apparently in the genus Flustra. "It 

 appears as a small spot, or spreads over a superficial area of various 

 extent, until equalling 2 or 3 inches, according to the specimen. The 

 diffusing edge is always curvilinear, the patch of dingy white, and sel- 

 dom thicker than writing-paper." " The upper surface is soft, wholly 

 composed of numerous cells, apparently with an elliptical orifice ; 

 and the lower or deeper part polyangular. However, the exact form 

 of the adult is not to be easily discovered ; and, in general, the real 

 figure of the cell seemed to me to be hexagonal." (p. 36.) We 

 suspect this is the same thing as the Flustra Peachii of Couch. 



The " Alcyonium" is the subject of Chapter 3. Plates 12, 13, 14 

 and 16 illustrate the multiform character of ^. gelatinosum ; plate 15 

 is a characteristic figure of A. hirsutum, here named A. palmatum ; 

 and the various figures in plate 17 are referable to the same species. 



Chapter 4 is entitled •' Miscellaneous Zoophytes." The first of 

 them described is Hydra (Coryna) squamata, pi. 18. figs. 1-10 ; but 

 the species is misnamed, for it is really the Hydractinia echinata. It 

 is well described, excepting in so far that the author seems to mistake 

 its muricated basis for the epidermis of the shell on which the zoo- 

 phyte has grown. The efforts of Sir John to breed the animal were 



