42 
THE VOYAGE OF H.M.S. CHALLENGER. 
The hydrothecse when traced to their origin from the axial tube are seen to be funnel- 
shaped, gradually tapering away from the orifice to the point of origin, and curving gently 
and with great elegance away from the supporting tube. The orifice is capable of being 
closed by the two membranous valves, which meet so as to form a ridge like that of the 
roof of a house, and which are composed of numerous, easily separated, very thin laminae. 
Cryptolaria geniculata is one of the three species in which the gonosome has been 
detected. While the two others — Cryptolaria abyssicola and Cryptolaria diffusa — have 
been dredged from the great depths of 2600 and 2500 fathoms respectively, the present 
species has been brought up from the comparatively moderate, though still very consider- 
able, depth of 315 fathoms. 
Cryptolaria gracilis, n. sp. (PI. XX. figs. 2, 2a). 
Trophosome. — Colony attaining a height of about two inches ; stem slender, flaccid, 
much and irregularly branched, and with the distal portion for a great extent destitute of 
the peripheral tubes. Hydrothecae alternate and distichous. 
Gonosome not known. 
Locality. — Station 169, near New Zealand ; lat, 37° 34' S., long. 179° 22' E.; depth, 
700 fathoms. 
Cryptolaria gracilis is an unusually well marked species. It forms small, tree-like, 
much-branched colonies, and while the slender flexile branches have their distal portions 
formed as in the other species by the free extension of the axial tube, this tube is 
here destitute of the peripheral investment for a greater extent than is the case in any 
other with which I am acquainted. It is apparently on this condition that the slender- 
ness and flaccidity of the branches mainly depends. 
Cryptolaria diffusa, n. sp. (PL XXI. figs. 1, la). 
Trophosome. — Stem slender, loosely and irregularly branched. Hydrothecse narrow, 
rather widely set, and with a nearly dichotomous arrangement. 
Gonosome. — Gonangia springing from distance to distance along the stem, flask 
shaped, about twice the width of the hydrothecse, curving away from the stem, solitary 
or geminate. 
Locality. — Station 101, off Sierra Leone; depth, 2500 fathoms. 
This is a very loosely branched slender form, with a straggling unattractive habit, 
and is of special interest from the great depth at which it has been found, and from the 
fact that it is one of the only three species of Cryptolaria in which the gonosome has 
been detected. 
