522 MATNARD M. METCALF, 



able that staining with methyl blue or gold chloride would show end 

 organs among these epithelial cells. 



The Molgulidae in general and Comparisons of the 



simple Ascidians. 



This family shows three points of special interest. The presence 



of rapheal ganglia in the Molgulas and in Herdmania is suggestive 



of metamerism, but in the absence of a knowledge of their development, 



the suggestion is of very doubtful value. 



In the representatives of this family I have studied, the rapheal 

 duct is rudimentary. 



The four species of this family I have described show an 

 interesting diversity in the relative positions of gland and ganglion. 

 Molgula manJiattensis has the gland almost dorsal to the ganglion ; in 

 Molgula arenosa (?) it is exactly on the right side; in Eugyra pilu- 

 laris it is dextro- ventral ; while in Herdmania it is very nearly ventral. 

 Thus within the hmits of a single family we have greater diversity 

 in the position of the gland than we have in all the rest of the 

 simple Ascidians. In the Cynthiidae the gland is dorsal; in the 

 Ascidiidae it is ventral; in the Molgulidae it may be either dorsal, 

 ventral, lateral, or ventro-lateral. In no Tunicate with which I am 

 familiar is the gland, or any of its appendages, on the left side of 

 the ganglion. 



Before discussing further the anatomy of the intersiphonal organs, 

 it is best to see their conditions in the compound Ascidians. 



The compound Ascidians. 

 The Botryllidae. 

 It will be sufficient to describe, as representatives of this family, 

 Botryllus gouldi Verrill, Botrylloides gascoi Della Valle and 

 Polycydus renieri Lamk. I have studied also Botryllus aurolineatus 

 GiARD, but it agrees so exactly with Botryllus gouldi that I shall 

 make no further reference to it. 



Botrt/Utis gouldi Verrill. 



Plate 37, Figs. 38-40. 



The neural gland of Botryllus suggests comparison with that of 



the Cîjnthiidae. (Cf. Plate 35, Fig. 19, a drawing of the gland of 



Boltenia.) The gland is directly dorsal to the ganglion and consists 



merely of a spindle-shaped enlargement of the duct, which in adult 



