REPORT ON THE HYDROIDA. 
87 
number of branches, which repeat in all respects the primary stems with their pinnae. 
In a magnificent specimen belonging to Mr. Busk, which was obtained in the Persian 
Gulf and attains a height of nearly a foot, the trophosome consists of numerous stems 
which spring in a close cluster from a plexus of tubular fibres. Soon after their origin 
almost all these stems appear to give off a great number of branches, and the specimen, 
instead of consisting essentially of a cluster of undivided stems with pinnately disposed 
ramuli, appears to form a profusely branched colony. The apparent branches, however, 
are in reality so many separate colonies which had attached themselves to the primary 
stems, which they grasp by their hydrorhizal tubules (PI. XXXIX. fig. 10). 
An entirely similar condition occurs in the Challenger specimens, both in those from 
the Philippine Islands and in those dredged off Bahia, none of which, however, possess 
a height of more than five inches, and in which the associated stems are but few. Among 
the Hydroids collected by the “ Rattlesnake ” is also a specimen of Idia pristis from the 
Australian Seas. Like the Challenger specimens it is of small size, and the separate 
colonies associated -with it in the form of branches are but few. 
Mr. Hincks lately sent me a specimen of Idia pristis which he had identified in a 
collection of Hydroids brought home from the Mergui Archipelago. The specimen, 
which is abundantly supplied with gonangia, presents a pseudo-ramification similar in all 
respects to that of the other examples here noticed. 
