70 THE VOYAGE OF H.M.S. CHALLENGER. 
the largest specimen, however, of this species dredged, These mandibles are very long 
and slender, three-jointed, little shorter than the proboscis. The third joint terminates 
in a pair of small and slender pincers. 
Of the palpi the third joint is longer than the fifth. Of the last three joints the 
first is extremely small and broad (Pl. IX. fig. 7), and the ninth is inserted, not into 
the middle of the front part of that joint, but quite laterally. This ninth joint itself 
is cylindrical, and more than twice as long as the foregoing, whereas the tenth is a little 
more slender and still longer than the ninth joint. 
The joints of the comparatively long ovigerous legs have characteristic proportions 
in all the species of the genus Colossendeis. The claw at the end of the tenth joint 
is very small. The denticulate spines on the last four joints are not numerous, the 
number of rows not exceeding four. Of these two are very regular, with the spines 
placed close to one another, but those of the two other rows are much more irregularly 
scattered over the remaining part of the inner surface of the joint (Pl. IX. fig. 8 ; 
Pl, A ig.7). A” 
The lengths of the’ several legs of one and the same specimen only show slight 
differences. The third leg is, in the three specimens I have examined, the longest, and 
measures nearly three and a half times the length of the body. The claw is very long,. 
still longer than the second tarsal joint. Genital pores are present on the second joint 
of every leg. As to the sex of the three specimens dredged during the voyage of 
H.M.S. Challenger, I have only been able to ascertain that the specimen with mandibles 
is a male. 
The body and legs are almost entirely smooth; small hairs are only to be observed 
on the last joints of the palpi. 
Habitat.—This species was dredged between the Cape of Good Hope and Kerguelen 
Island. 
Station 146. December 29, 1873. Lat. 46° 46’ S., long. 45° 31’ E. Depth of the 
sea, 1375 fathoms. Temperature of the bottom, 1°5°C. Bottom of the sea, globigerina 
ooze. ; f 
Station 147. December 30, 1873. Lat. 46° 16’S., long. 48° 27’ E. Depth, 1600 
fathoms. Bottom temperature, 0°8° C. Bottom of the sea, globigerina ooze. 
Observations.—To this species Colossendeis media and Colossendeis brevipes, which 
I shall describe further on, are closely allied. The occurrence of mandibles in one of 
the specimens of this species is very interesting. Although larvee of any species of 
Colossendeis have never been observed, they doubtless are furnished with three pairs of 
cephalic appendages. Of these the adult animal has always lost the first pair; and 
whenever, as in the case in question, this first pair is observed in the adult animal, it 
must be considered as a case of atavism, showing that the loss of mandibles in the 
adult animal has been’ comparatively recent. 
