300 Mr. W. N. Lockingtou on Nurtli-Amencan 



While most of the smaller individuals are accompanied by 

 a pair of P. abdominalis^ the larger specimens were free from 

 this crustacean J but in many cases bore the mollusk above 

 mentioned. 



In only one case, out of over a hundred s])ecimcns dug up 

 in Tomales Bay, were the mollusk and the Isopod found in 

 company upon the same Gehia ; and in this case the Gehia was 

 of middling size, and the mollusk very small. On specimens 

 collected July 4 I did not find the bivalve, and the Phyllo- 

 durus was less common than in May. 



In San-Francisco Bay I have not as yet detected Pythina 

 rugifera^ but Phyllodurus is sufficiently common. 



Gehia pugettensis is on record from various points along the 

 Pacific coast from Puget Sound to Monterey, and also from 

 San-Quentin Bay, west coast. Lower California. 



Gehia spinigera^ S. I. Smith. 



Gehia spinigera, S. I. Smith, Report Peabody Acad. Sci. 1869, p. 92. 



A large number of specimens, all females, were collected by 

 J. A. M'Neil, at the island of Aseredores, 20 miles north- 

 west of Corinto, Nicaragua ; and a few were also collected in 

 the Gulf of Fonseca. 



Gehia longipoUex^ T. H. Streets. 



Gehia longipolUw, T. H. Streets, Proc. Acad. Nat. Sci. Phil. Dec. 1871, 

 p. 242. 



This species, having a tridentate front, and a small spine 

 on the carapax over each antenna, is described in a " Cata- 

 logue of Crustacea from the Isthmus of Panama," collected 

 by J. A. M'Neil, and probably came from the Pacific coast of 

 the isthmus. 



Gehia rugosa, nov. sp. 



Rostrum short, thick, obtuse at tip, curved downwards to 

 the level of the centre line of the cornea of the eye. Upper 

 orbital margin curving outwards convexly ; margins of an- 

 terior portion of carapax, posterior to the curve, straight, but 

 gradually divaricating. Upper surface of rostrum and cara- 

 pax, to about halfway to the dorsal suture, beset with small 

 tubercles and hirsute. 



Cornea black, visible from above between the rostrum and 

 the outward curve of the carapax. 



Antcnnai projecting beyond rostrum to a length about equal 

 to that of carapax, sparsely setose. 



