DESCRIPTIONS OF FOUR NEW SPECIES OF AMPHIPO- 
DOUS CRUSTACEA FROM THE GULF OF MEXICO. 
By Arruur 5S. Pearse, 
Of Harvard University, Cambridge, Massachusetts. 
The species here described form a small part of a collection of 
amphipods from the Gulf of Mexico which was sent to the author 
for study by the United States National Museum. As lack of time 
prevents the completion of a full report in the near future, it is 
thought best to publish now the new forms already discovered. 
The type specimens are in the United States National Museum. 
AMPELISCA HOLMESII, new species. 
Cephalon about equal to first 8 segments of mesosome, tapering 
anteriorly, truncated, first coxal plate slightly expanded distally, 
broader than second, about same width as third, fourth plate deeper 
than broad, lower edge much shorter than posterior margin. Last 
ephimeral plate of metasome produced at posterior ventral corner, 
bisinuate; both the process and lobe are less pronounced than in A. 
macrocephala Lilljeborg. First segment of urosome with a slight 
dorsal transverse depression and behind it a low carina (more distinct 
in male) with a shght projecting angle. Corneal lenses small but 
distinct, lower pair occupying inferior corners of cephalon. First 
antenne about the length of the cephalon, reaching only slightly 
beyond the tip of the second segment of the peduncle of the second 
pair, those of the male reaching almost to tip of third segment, 
flagellum 8-segmented. Second antenne in female scarcely half the 
length of body, third joint of peduncle shorter than second. Gnatho- 
poda slender, propodus in first about the length of the carpus and 
shehtly tapering distally, that of the second about half as long as the 
carpus and slender. Dactylus of first two perszeopoda much longer 
than two preceding segments combined. Last pair of perzeopoda 
with the basal joint almost as long as remainder of leg, posterior 
PROCEEDINGS U.S. NATIONAL MUSEUM, VOL. XXXIV—No. 1594. 
Px) 
