46 
THE VOYAGE OF H.M.S. CHALLENGER. 
Perisiphonict pectinata is the result not only of the small number of peripheral tubes 
which enter into their composition, but of the fact that both peripheral and axial tubes 
are themselves more slender in this species than in the other. While the number of 
peripheral tubes in the pinnae of Perisiphonict filicula is as many as ten or possibly more, 
I have always found the number of these tubes in the peripheral fascicle of Perisiphonia 
pectinata to be limited to six. 
The superficial sarcothecal system is particularly well developed in Perisiphonia 
pectinata, in which the sarcothecse are considerably longer than in Perisiphonia jilicula. 
They spring from the peripheral tubes by a slightly dilated base. 
Family GRAMMARIDiE. 
Character of the Family. Trophosome. — Hydrocaulus consisting of an axial tube 
which carries the hydrothecse, and is entirely surrounded by a definite number of 
peripheral tubes which are destitute of hydrothecse. Axial and peripheral tubes 
inseparably coalesced. All the hydrothecse adnate by their sides to the axial tube. 
Hydranths with conical hypostome. 
Gonosome not known. 
Grammaria, Stimpson. 
Gcimmaria, Stimpson, Marine Invertebrata of Grand Manan. 
Generic Character A Trophosome. — Colony, a ramified hydrocaulus composed of a 
fascicle of longitudinal tubes definite in number and inseparably adnate to one another, of 
which one is axial and the others peripheral, the axial tube entirely covered by the 
peripheral, and sending off, from distance to distance along its length, tubular, non- 
pedunculated hydrothecse, which are at first adnate to it by their sides, and then, passing 
between the peripheral tubes, reach the surface of the fascicle, where they form|definite 
longitudinal series directed on all sides round its circumference. 
Gonosome not known. 
The tubes which are combined into the fascicle which forms the stem and branches of 
the colony in Grammaria are very definite in number and arrangement, though their 
close adhesion to one another renders it difficult to determine their exact relation to the 
hydrothecse. One of these tubes always occupies the axis of the fascicle and gives off 
from distance to distance the hydrothecse, which are at first inseparably adnate to the 
tube from which they spring, and then, becoming free, bend outwards between the 
peripheral tubes so as to reach the surface of the fascicle, and thence project into the sur- 
rounding water. 
1 The facts brought to light by a study of the specimens of Grammaria obtained by the Challenger have rendered 
necessary a fundamental revision of the characters hitherto regarded as diagnostic of this genus. 
