1897 - 98 .] Prof. D’Arcy W. Thompson on Marine Faunas. 325 
able, and the branchiae are absent.” He cites it as Eupistes Dar- 
wini , var., saying that, from that species, “ sufficient materials are 
not at hand to establish a reliable distinction if such exist.” 
Terebellides Stromi, M. Sars. — The specimens of Terebellides 
taken by the “ Challenger ” at Kerguelen are grouped by MTntosh 
with the northern species under the name of T. Stromi , var. Ker- 
guelenensis. 
Placostegus ornatus, Sowerby. — This little tubicolous annelid is 
recorded in the Challenger Report from 2900 fathoms, lat. 35° 22' 
N., long. 169° 53' E., in the deeps of the North Pacific; again, 
from 3125 fathoms further west in the same area, and from 2375 
fathoms, lat. 32° 36' S., long. 137° 43' W,, south of the Paumotu 
group. Other species of the same genus inhabit the British area, 
the West Indies, the deep water of the Mid-Pacific, etc. 
Ostracoda . — Eight species of Ostracoda are enumerated in Dr 
Murray’s list on the strength of the Challenger collections. In 
regard to two of these, Krithe tumida , Brady ( Rep ., “ Ostracoda,” p. 
115), and Xestoleberis expansa, Brady (p. 129), I cannot discover 
any reference to their occurrence in the north. In regard to most 
of the others, considerable dubiety is expressed by Dr Brady in 
regard to their identity ; for example, in reference to Paradoxo- 
stoma abbreviation, G. 0. Sars (op. cit., p. 150), he says, “As no 
very decided characters appear, and as no sufficient series of speci- 
mens of the Kerguelen form is at hand for comparison, it seems 
best to identify them, for the present at least, with the European 
species.” Cythere suhmi, Brady, and Sclerochilus contortus, Nor- 
man, were represented in their southern localities only by imperfect 
specimens or separated valves. Xestoleberis depressa, G. 0. Sars, 
is a northern species recorded by Brady from Kerguelen, with the 
remark, “it is to be borne in mind, however, that the distinctions 
between this and the next species (X. setigera, Brady, from Ker- 
guelen, Heard Island, etc.) if valid at all, are very slight, and it is 
not unlikely that the two may prove to be identical.” 
Furthermore, it behoves us to remember that the study of the 
Ostracods is now conducted in a totally different way, and stands 
on a different basis, compared with the period when the Challenger 
monograph was prepared. The Challenger species were identified 
by the form and sculpture of the shells alone, without reference to 
