4 
THE VOYAGE OF H.M.S. CHALLENGER. 
to one and the same division of the genus. I have been able to study the male of one 
of these ( Scalpettum regium [Wyv. Thoms.], Hoek) more in detail ; in all essential 
respects the males of the other twelve agree with it. 
The twenty-four species of Scalpettum, the males of which are known at present, may 
be classified with regard to the structure of these males in the following way : — 
A. Species, the males of which show a distinct capitulum and peduncle : — 
Scalpettum peronii, Gray, sp. Scalpettum rostratum, Darwin. 
Scalpettum villosum, Leach, sp. 
All these are shallow water species. 
jB. Species, the males of which do not show a division of the body into a capitulum 
and a peduncle, but yet are furnished with rudimentary valves : — 
Scalpettum vulgare, Leach. 
rutilum, Darwin. 
ornatum, Gray, sp. 
intermedium, Hoek. 
Scalpettum parattelogramma, Hoek. 
elongatum, Hoek. 
tritonis, Hoek. 
triangulare, Hoek. 
Species occurring in depths varying between shallow water and 700 fathoms. 
C. Species, the males of which do not show a division of the body into a capitulum 
and a peduncle, and are not furnished with rudimentary valves : — 
Scalpettum marginatum, Hoek. 
stromii, Sars. 
compressum, Hoek. 
nymphocola, Hoek. 
velutinum, Hoek. 
eximium, Hoek. 
Scalpettum gigas, Hoek. 
regium (Wyv. Thoms. ) , Hoek. 
darwinii, Hoek. 
tenue, Hoek. 
dubium, Hoek. 
fiavum, Hoek. 
Scalpettum pedunculatum, Hoek. 
With the exception of three {Scalpettum pedunculatum, Scalpettum stromii, and 
Scalpettum nymphocola), these species occur in depths of upwards of 1000 fathoms. 
The depths at which Scalpettum stromii and Scalpettum nymphocola were collected are 
less considerable ; these species, however, belong to the arctic fauna, which, as is well 
known, shows numerous instances of deep-sea animals occurring in rather shallow water. 
Scalpettum pedunculatum was taken from a depth of 150 fathoms only. 
