Notes on the morphology of the T^unicata. 527 



may indicate that these two conditions are but different stages in the 

 process of secretion. It is not, however, sufficient proofs). 



Circinalium concrescens Giakd. 



This species needs no description beyond saying that here, even 

 more clearly than in Amaroecium and Fragaroides, the rapheal cellular 

 cord is seen to be a prolongation of a mass of cells derived from 

 both ganglion and gland, but chiefly from the gland. 



The lumen of the gland is usually completely filled with a mass 

 of cells such as the one shown in Fig. 49 of Plate 37. Here, as in 

 the gland cells of Edeinascidia (cf. Plate 34, Fig. 12), the vacuole 

 contains a central coagulum, probably due to reagents. This stains 

 much less deeply with haematoxylin than does the peripheral proto- 

 plasm of the cell. In a few cells of the gland, instead of a large 

 vacuole with a single central coagulum, we find one, two or three 

 paranuclear bodies in the cytoplasm of the unvacuolated cell. 



The Bidemnidae. 



Leptoctinum albidum Verrill, is my only representative 

 of this family (Plate 37, Fig. 50). 



Leptoclinum has large vesicular cells in the gland (Fig. 50). The 

 gland, which is large compared with the minute size of the animal, 

 lies well back of the ganglion above the upper end of the dorsal 

 raphe. From the ganglion above it, a slightly gangliated nerve (not 

 shown in the figure) pushes back around the posterior end of the 

 gland to reach the raphe into which it passes. 



The rapheal nerve is not large and its ganglion cells are few in 

 number. The rapheal muscle on the other hand is phenomenally large 

 in this species compared to the minute size of the individuals. This 

 discrepancy in size between the nerve and muscle apparently indicates 

 that the innervation of this muscle is not the sole function of the 

 nerve. If this be true of one species it is probably true of all. 



1) Maumce figures the gland cells as stellate and forming a net- 

 work. This is somewhat misleading. Inasmuch as the central portions of 

 the vesicular cells stain less deeply than their peripheral cytoplasm, a 

 mass of these cells does at first glance seem like a mass of stellate 

 cells (cf. Fig. 47). 



Zool. Jahrb. XHI. Abth. f. Morph. 35 



