DECAPODS 5 
abundant species are Pandalus borealis and P. montagui, both 
boreal forms which descend from the Arctic regions into the At- 
lantic as well as the Pacific, but in the latter find conditions most 
favorable to their increase. The form of P. montaguz inhabiting 
the Pacific exhibits modifications which entitle it to recognition 
as a distinct subspecies. 
In number of species the genus Sfzrontocaris of the family 
Hippolytide is unsurpassed. Like Pandalus, it is primarily a 
boreal genus, and is common to the Atlantic and the Pacific. In 
the Pacific it is represented by 51 species, exhibiting great diver- 
sity inform. Several are identical with Atlantic species. 
Quite as conspicuous in the North Pacific fauna are the Cran- 
gonidz. These occur in great numbers, and exhibit 32 different 
forms, for the most part restricted to the Pacific. 
The Paguridz, or hermit-crabs, occur in vast numbers, and some 
of the species appear to have local centers of distribution. Each 
of these species attains its maximum development, both as to size 
and numbers, in a particular area, while elsewhere it is stunted 
and infrequent. 
Several of the spider-crabs (Maiide) abound in shallow as well 
as in deeper water, and Oregonia, Chorilia, the two Chionecetes, 
and the two species of Hyas form no inconsiderable part of every 
haul of the dredge. 
Less abundant are the Lithodide or Anomuran spider-crabs, 
which include the giant Decapods of the region. 
The crowding of crustacean life in certain localities is especially 
favorable to parasitism. Bopyrids (of a few species only) are of 
frequent occurrence on many species of shrimps'; Rhizocephalids 
are less common, while worm parasites have been noticed in sev- 
eral instances embedded underneath the carapace of Spzrvontocarts. 
The Decapods contribute without doubt a large proportion of 
the food of fishes, several species having been taken from their 
stomachs; but our knowledge on this subject is very fragmentary. 
Many species are caught for the market, to be used for the 
table or for bait. The list of these furnished in ‘The Fisheries 
and Fishery Industries of the United States,’ Washington, 1884, 
1Miss Harriet Richardson will publish a report on the Bopyridz of the Museum 
collection in the Proceedings of the U. S. National Museum during the next year. 
