[From the Annals and Magazine of Natural History for 

 October 1878.] 



Remarks upon the Thalassinidea and Astacidea of the 

 Pacific Coast of North America^ with Description of a 

 new Species. By W. N. LoCKiNGTON. 



Thalassinidea, 

 Family Gebidse. 



Gehia pugettensis^ Dana. 



Gebia puffettensis, Dana, U.S. Ex. Exp., Crust, i. 510, pi. xxxii. fig. 1 ; 

 Stimpson, Crust. & Echin. P. S. N. Am. p. 48. 



This species is exceedingly abundant in San Francisco and 

 Tomales Bays, and frequently attains a length of six inches 

 or even more. 



The subterranean passages made by it are usually nearly 

 perpendicular, about an inch across, and very neatly rounded 

 in section, with the walls smooth as if plastered, the smooth- 

 ness resulting entirely from the pressure of the animal's body 

 as it pushes itself upwards and downwards by the action of 

 its terminal abdominal segments. 



The burrows are not confined to strata of sand, but are 

 abundant also in mud, in sandy shingle, and even among 

 rocks, ranging upwards almost to high-water mark, and 

 downwards to at least three or four fathoms, since large speci- 

 mens were brought up in abundance by the dredging-machines 

 in Oakland Harbour. 



Almost every specimen collected in Tomales Bay, in the 

 month of May, bore upon its abdominal feet either the curious 

 Isopod Fhyllodurus abdominalis (Stimpson, op. cit. p. 71), or 

 a small bivalve mollusk, Pythina rugifera^ Carpenter. 



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