NO. 1350. NATURAL HISTORY OF THE ISOPODA— RICHARDSON. 29 



Syscenus infellx Harj^er, lioclnehi duinerili (Lucas), and iJajus 

 )iii/si(Us Kr0yer. 



Clilrldotca sablni (Kr0yer) i,s a circumpolar species, ha\ino- ])ccn 

 recorded from the Pacific coast of North America, Greenland, the 

 Siberian Pohir Sea, the Kara Sea, and Franz-Josef Land (Sars). 

 Synldotea nodnlom (Kr03'er) is also circumpolar and occurs along the 

 west and east coasts of North America. 



Some of the Bopj'rida^ have a wide distribution. Phryxus ahdouil- 

 nalln (Kr0yer) has been recorded from the coast of Norway, from 

 Greenland, and from the Atlantic and Pacific coasts of North America, 

 the various species of host which it infests being circumpolar. Bvpy- 

 roides hippolytes (Kr0yer) is found also on both coasts of North Amer- 

 ica, the form from the west coast having been described b}^ Stimpson 

 under the name acutlmarginata. 



It is interesting to note the similarit}' between several of the species 

 found on the Atlantic coast of North America and those of the Pacific 

 coast, the difi^erences separating them being very slight. Hansen has 

 pointed out the close resemblance of his two species ^Ega iiiax'ima^ 

 from Cocos Island, and u.Ega acuminata., from the Galapagos Islands, to 

 uEga psora (Linnteus) from the Atlantic coast; of his species ^Ega 

 plebela from Cocos Island and the Galapagos Islands, to ^Ega ventrosa 

 Sars from the coast of Greenland; of his species Rocinela niodesta., 

 from the Gulf of Panama to Roclnda maculata Schioedte and Meinert, 

 from Greenland, and of his species Rocinela laticauda from the coast 

 of Mexico to Rocinela australin Schioedte and Meinert from the Straits 

 of Magellan. Rocinela affinis Kichardson from Japan also presents 

 striking resemblances to Rocinela oculata Harger from the Atlantic 

 coast of North America. Cilicsea caudata gilliana Richardson and 

 Dyn((mene iuherculosa Richardson from the Pacific coast are quite 

 similar to forms from the Atlantic coast, Cilicsea caudata (Sa}") and 

 Dynaniene hermadensis (Ives) from the Gulf of Mexico, Yucatan, and 

 the Bermudas. 



A rather remarkal>le instance of a shallow-water organii^m coming 

 from two very remote localities is that of Lejdochelia niinuta Dana. 

 The type .species of this form was obtained from the Fijis, at the 

 island of Ovalau, from among seaweed and small corals. A, few 3'ears 

 ago this species was again recorded by Stebbing, but this time from 

 the West Indies, at Long Island, where it was found in shallow water 

 covered with alga'. 



In the present paper record is made of a species ^Ega deshaysiana 

 (Milne Edwards) known to West Indian waters, being obtained by the 

 U. S. Fish Commission steamer Allxdro-ss at the Hawaiian Islands. 



In explanation of these facts Dr. Gill has said: 



The infereiu'e is irrcsistil)le that sui-li types liavi' luijirated from common ground, 

 and may have originally developed either in the deep 8ea and thence dispersed in 

 opposite directions, or at one of the extremes, anil wandered thence over the bot- 

 tom to their final resting places. 



