62 
THE VOYAGE OF H.M.S. CHALLENGER. 
equal rank, and I think it is simpler to call them all genera. Consequently I return to 
Lamarck’s view, and consider Polycyclus as a distinct genus. It is characterised by the 
proportions of the colony, the shape of the systems, and the position of the apertures 
and form of the body in the Ascidiozooid. 
The colony, hke that of Sarcobotrylloides, is thick, forming a large and usually lohed 
mass in place of a thin crust as in Botryllus and Botrylloides. The systems are stellate, 
with circular outlines as in Botryllus, and thus differ from those of Botrylloides and 
Sarcobotrylloides. The Ascidiozooids of Polycyclus have the ovoid form with distant 
apertures, which is found in Botryllus. The possession of two laterally placed tooth-like 
tentacles is also given by von Drasche as a character of the genus, hut as I do not find 
that feature in the new species described below, which are in all other respects typical 
members of the genus — I leave out this characteristic. In one of the new species the 
tentacles are eight in number, in the other sixteen, and in neither do two predominate 
over the others, consequently the tentacles of the genus must be regarded as varying 
from two to sixteen. 
A number of species have been described which may be referred to this genus, but in 
the cases of the older of these it is very uncertain how far they are distinct from one 
another. Some of them are very imperfectly known. 
Lamarck described Polycyclus renierii, and this is probably not the species described 
by Savigny as Botryllus polycyclus. Della Valle suggests that the Polycyclus elongatus 
of Delle Chiaje is simply a variety of Polycyclus renierii, a species which he describes in 
detail. Grube also discusses Polycyclus renierii and a slightly different form which he 
regards as a variety. Two new species, Polycyclus cyaneus and Polycyclus violaceus, were 
described by von Drasche in 1883. Leaving out the uncertain forms, the genus may be 
divided as follows : — 
Polycyclus. 
Ascidiozooids at Ascidiozooids not 
least 3 mm. long. 3 mm. long. 
Two tentacles. More than Eight tentacles. Sixteen tentacles 
I two tentacles. | | 
P. cyaneus. [ P. lamarcld. P. Jeffrey si. 
• I n 
Ascidiozooid Ascidiozooid. 
at least 3 mm. long. 
4 mm. long. | 
I P. violaceus. 
P. renierii. 
The two new species were both obtained during the “ Porcupine ” expeditions, 
Polycyclus lamarcld in the Faeroe Channel from a depth of 363 fathoms, and Polycyclus 
jejff'reysi from Tangier Bay in the Mediterranean, in shallow water. 
