426 
distance from the median line and gradually increase in length to the 
anterolateral angle; this series of teeth is continued inward toward the 
median line by small, and progressively smaller, spines; the lateral edges 
are slightly produced and smooth; the anterolateral angles bear à few 
prominent blunted spines; in the center ofthe ossicle there isa prominent 
and sharp, though not especially high, median keel; the axillaries are 
broadly rhombic, the lateral angles truncated, about twice as broad as 
long; the lateral edges are not quite so long as those of the IBr; and 
are produced and irregularly and coarsely spinous; the distal edges and 
the outer part of the proximal edge are slightly everted and finely spi- 
nous; a prominent keel resembling that on the IBr,, runs nearly its 
whole length; nine IIBr series are present, all 4 (3-+-4); they resemble 
the [Br series and, like them, are prominently carinate; their lateral 
borders are produced and are irregularly denticulate or spinous; nine 
IIIBr series are present, all 4 (344), resembling the IIBr series; the 
produced and denticulate borders extend as far as the base of P, exter- 
nally and as far as the fifth or sixth brachial internally. 
The twenty-eight arms are about 120 mm long and in general re- 
semble those of Th. gigantea; the first two brachials are carinate; the 
following have slightly everted and finely spinous distal edges, and have 
the dorsal’ (but not the lateral) surface covered with very numerous short 
fine spines; as the brachials become triangular the proximal edges lose 
their eversion while that of the distal edges becomes recumbent and 
more prominently spinous; the spinosity of the dorsal surface gradually 
becomes arranged in definite lines forming a series of sharp serrate 
longitudinal striations. 
Type Locality. — »Siboga« Station No. 251. 
Thalassometra margaritifera sp. nov. 
This new form is very close to Th. hirsuta; the eversion of the 
proximal and distal edges of the ossicles of the [Br series and of the 
first two brachials is less marked than in Th. hirsuta and the spinosity 
is coarser, the spines being more uniform in size and more thickly dis- 
tributed over the dorsal surface of the ossicles; they are also more nume- 
rous and longer on the dorsal surface so that there is less difference 
between the spines of the dorsal surface and those of the everted edges; 
the median carination is more rounded than that of Th. hirsuta and is 
studded with spines resembling those of the general dorsal surface. 
Type Locality. — »Siboga« Station No. 45. 
Thalassometra perplexa sp. nov. 
This new form is closely related to Th. pergracilis, from which it 
differs in having the calyx smooth with merely a trace of a thickening 
