10 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 
T have also examined specimens taken by Alexander Agassiz on the 
Blake in 1880, at the following stations : 
| Station. N. lat. W. long. Fathoms. | Specimens. 
| ° ‘ “ [o} ‘ uw 
335 | 38 22 25 | 72 33 40 89 1 
B45n 40) MO] 1b gies cop 71 10¢ 9 
346; 40 25 35 | 73 10 30 44 1 
Among the vast number of specimens examined there are very few 
sexually immature individuals. Both sexes ordinarily attain maturity be- 
fore the carapax is 6™ in length, and the scarcity of immature speci- 
mens in the collections may be due to their small size causing them 
to be overlooked in the great mass of material brought up in the trawl. 
The largest females seen do not exceed 10™™" in length of carapax, 
and differ very little from the smallest in the form and proportions 
of chelipeds and ambulatory legs, though the carapax is a little broader 
in proportion and the spines with which it is armed are much lower, or 
reduced to tubercles, in the larger specimens. The males attain much 
greater size than the females, the carapax often exceeding 14™™ in 
length, and there is a very marked and constant increase in the size 
of the chelipeds, particularly in the height and the thickness of the 
body of the chele, well shown in the accompanying table of measure- 
ments. In both sexes there is considerable variation in the length of 
the spines of the carapax, even in specimens of the same size, and there 
is a marked decrease in the length of the spines with the growth of the 
individual. In large specimens the spines upon the orbital arches, upon 
the gastric, cardiac, and the summits of the branchial regions, and 
upon the basal segment of the abdomen, are usually reduced to low, 
and often inconspicuous, tubercles. 
The number and arrangement of the branchiw and epipods are indi- 
cated in the following formula: 
| Somite— H 
; l he WNRUEAT wR TSS. Ps 
Walter b| VAL TI pl palexe ee Ser. SI) MELT. 1 SKVy. 
| 
eek eg | -|— aioe eae eee 
‘Huipndkese 2 ete 1 0 | 1 | 0 0; O| 0 | 0 (2) 
. | H 
Podobranchiw.-..........: 0 1 1 0 | 0 07 0: 0!2 
Arthrobranchiw.......-. 4 0 | 0 | 2 0 | 0 0 0 | Oreo 
Pleurobranchiw......... 0 0 | 0 | 2 1 TS 0 0\4 
| | \ | -_-_- 
| | | | | | 8+ (2) 
I | L 
The sixth and seventh somites of the abdomen of the male are an- 
chylosed completely, as they are also in ELuprognatha rastellifera, Col- 
