242 STALK-EYED CRUSTACEA. 



An analysis of this list discloses the enormous — often cosmopolitan — 

 distribution of deep-sea types and their lack of special affinity with the 

 nearest littoral fauna. Only four new genera were found among the Stalk- 

 e^'ed Crustacea taken at a greater depth than 500 fathoms, viz. Trachycar- 

 cinus, Calastacus, ScoIojyJithalmus, and Ceratomysls. Of these, Trachycarchms 

 (a Corystoid crab from 546-G95 fathoms) is represented in deep water in the 

 Caribbean Sea by an undescribed species which is probably congeneric, and 

 by TrichojjeJtarion (151 fathoms). Both of these genera are closely related 

 to, and perhaps derived from, HyjKypcltarium, a shallow w\ater form found on 

 the shore of South America from La Plata around Patagonia to Chile. Calas- 

 tacus is allied to Calocaris of the North Atlantic, 150-400 fathoms. Scoloph- 

 ihahnus, a deep-sea Schizopod, is probably a near relative of liansenomysis 

 from off the west coast of Greenland, and it is worthy of note that both 

 ScolojMialmns and Ceratomysls confess by their structure their kinship with 

 Boreomysis, a genus which reaches its highest development near the arctic 

 and antarctic regions. 



Iconaxius has been previously known from remote parts of the Pacific, — 

 near the Celebes and Kermadec Islands. The only other known species of 

 Paracrangon inhabits Puget Sound and the seas near Japan. Sckrocrangon is 

 without doubt a genus of boreal origin. It is represented in high northern 

 latitudes by circumpolar littoral species, and on both sides of the Atlantic by 

 deep-water species that range as far south as 31° 57' N. (*S'. agassizii). One 

 of the " Albatross " west coast species, S. procax, extends the range of this 

 genus southward in deep water to within 4° 3' of the equator (Station 3380, 

 899 fathoms, bottom temperatui'e 37° F.). The genus Pandcdopsis is repre- 

 sented in the "Albatross" collection by the same species that was discovered 

 by the " Challenger" off Monte Video. Petalopldlialmus was known, prior to 

 the "Albatross" Expedition, only through the unicjue specimen obtained by 

 the "Challenger" Expedition from a great depth in the tropical Atlantic. 

 Like Scoh)2)ld]ialmus and Ccratomysis, it is related to Boreomysis. All the 

 other genera included in the aboye list may be said to have a world-wide 

 distribution. 



That the truly deep-sea Crustacean fauna of the Panama region has no 

 special affinity with the littoral fauna of the same region may perhaps be 

 more clearly shown by placing in two columns the distribution of the 

 Panamian species found below 500 fathoms, or the habitat of representative 

 species, when such are known. 



