W. G. Van Name — Bermuda Ascidians. 387 



The tentacles are long* and more or less brown-pigmented. Ver- 

 rill gives 40 as the number in the type specimen of P. midtiphiala, 

 but this number is sometimes exceeded. They vary somewhat in 

 size, but no very regular arrangement, except an alternation of 

 larger and small ones, is to be distinguished. Traustedt gives 36-40 

 as the number of tentacles. 



The dorsal tubercle is large ; the opening is horseshoe-shaped with 

 incurved, but not spirally rolled, horns. (This was the condition in 

 several specimens examined and agrees with Traustedt's description). 



Traustedt states that there are 4 folds on the left and 5 on the 

 right side. Sluiter mentions one specimen with 4 on each side. 

 This I have found to be the case in most of the Bermuda specimens 

 examined, though in one case a rudimentary fifth fold was present 

 on the right side, next to the dorsal lamina. The folds are generally 

 wide. The one nearest the dorsal lamina is the smallest. The 

 internal longitudinal bars are very wide and flattened. They are 

 quite numerous, about four or five occurring between the folds, and 

 sometimes as many as' 10 or 11 on one side of a fold. They are sep- 

 arated by 10 or 12 stigmata in the spaces between the folds (14 near 

 the endostyle). This number diminishes to 3 or 4 or less near the 

 summit of the folds, where the bars are so close together that when 

 flattened down against the branchial sac they overlap each other for 

 most of their width, covering the intervening stigmata entirely. 

 The transverse vessels are of various sizes, but are not arranged with 

 great regularity. Small transverse vessels crossing the stigmata 

 without interrupting them are generally wanting. 



The alimentary loop is of the same color as the mantle and 

 branchial sac. It forms in some cases a moderately large, open loop ; 

 in others a much narrower one (see figs. 92, 93 and 94). The 

 stomach is small. In all cases the alimentary loop is confined to the 

 posterior half of the body. 



The gonads are distributed to the number of 20 or more on each 

 side of the body. They are flask-shaped bodies, and are so placed 

 that their orifices are directed toward the atrial siphon. The central 

 part of each is occupied by the ovary, and the oviduct opens at the 

 extreme end of the gonad. The sperm-duct opens on a separate 

 papilla or projection a little distance from the end, and is formed by 

 the union of two branches, one of which runs along each side of the 

 ovary and receives the ducts from the numerous small pyriform 

 testes. (Figs. 88 and 89.) In these figures the ovaries are not fully 

 ripe, and the gonads have an elongated phial-like form. This is one 



