ZOOLOaY AND BOTANY, MICEOSCOPY, ETC. 231 



Within the orifices of the Ascidians is a thin layer of tissue, 

 which is evidently a continuation of the exterior tunic, and is styled 

 by the author " tunique reflechie." The free surface of this is in some 

 species covered with three distinct forms of microscopic bodies — 

 needles, scales with rounded niargins, and forked scales. At their 

 base, between the thicker prolongations of their margins, is a large 

 nucleus, readily coloured by reagents, and often surrounded by 

 protoplasmic particles endowed with a very marked movement, which 

 evidently proves the cellular origin of these scales. Other species 

 are free from the bodies in question, and the author therefore divides 

 the Cynthiidae into armed and unarmed. 



To determine the species of Cynthia all that is necessary is to 

 remove a minute portion of the reflected tunic from an extended 

 orifice with sharp scissors and place it under the Microscope. The 

 scales require high powers, sometimes 400-500. 



Doliolum.* — B. Uljanin has a monograph on this remarkable 

 Tunicate, the life-history of which he groups somewhat differently 

 to his predecessors — Gegenbaur, Fol, and Grobben. The larva gives 

 rise to the " nurse-generation," which has a ventral stolon, and nine 

 muscular bands ; the stolon gives off primitive buds, which form the 

 material for the sexual generation ; this is polymorphous, and contains 

 three forms ; (a) the nutrient animals are abnormally constructed, 

 have no generative products, and serve to nourish the nurses ; (/S) 

 foster-animals, which have eight muscular bands, no generative pro- 

 ducts, but serve for the production of the buds whence the (y) gene- 

 rative animals are formed ; these last have eight muscular bands, and 

 completely developed generative organs; their ova give rise to the 

 tailed larvee. 



The first chapter gives a schematic account of the structure of 

 Doliolum, of the structure of the generative animal, and of the mode 

 of development of the ova in the ovary. In the second chapter we 

 have a history of the development of the larva from the egg, from 

 which it seems to be clear that the enteric cavity (including the 

 pharyngeal cavity) of Doliolum is not the homologue of the same 

 parts in the Ascidians, nor the cloacal cavity of Doliolum that of the 

 atrium of Ascidians. It enables us also to come to some conclusions 

 as to the morphology of the rudiment of the nervous system ; it opposes 

 the view of Julin that the ciliated pit of Tunicates is the homologue 

 of the hypophysis cerebri of Vertebrates; the branchial nerve of 

 Doliolum is not part of the peripheral nervous system, but can be best 

 compared to the nerve-cord found in the tail of larval Ascidians. 

 The third chapter deals with the conversion of the larvae into the 

 nurses, and the structure and metamorphosis of the nurse ; many 

 points with regard to the latter have been already well treated of by 

 Grobben. 



In the fourth chapter the separation of the primitive buds from 

 the^ stole prolifer of the nurse is described ; these buds wander, and 

 divide again into buds, which, in their turn, become fixed to the out- 



* Fauna und Flora des Golfes von Neapel, x. (1884) 140 pp. (12 pis.), 



