Thalassinidea and Astacidea. 301 



Antennulse less than half the length of antennae, branches 

 of flagella equal, the upper stouter than the lower. 



Chelipeds equal; merus compressed, smooth, equal in length 

 to the hand ; carpus smooth, about half the length of upper 

 margin of propodus ; propodus smooth, sparsely hirsute, the 

 hairs most abundant on inner side ; pollex short, sharp- 

 pointed, curved regularly upwards ; dactylus less than half 

 the length of palmar portion of hand, which is thickly hirsute, 

 curved regularly downwards, its tip passing beyond that of 

 the dactylus. 



Four hinder pairs of pereiopodi compressed, the posterior 

 margins and tips of the propodi hirsute, also, to a less extent, 

 the posterior margins of the carpi. 



Anterior margin of the merus and propodus of the second 

 pair set with long hairs. 



Posterior margin of fourth abdominal segment beset with 

 short stiff hairs ; the three posterior segments and the lateral 

 caudal appendages complexly wrinkled above, the rugge 

 smooth. Terminal segment broader than long, distal margin 

 longer than proximal ; caudal processes large, filling up the 

 space between the terminal and fifth segments. 



Length of larger specimen 25 milliras. 



Two specimens of this species were collected at Port Escon- 

 dido. Gulf of California, under stones and coral at low tide, 

 August 1876. 



CalUanassa californiensisj Dana. 



Callianassa californiensis, Dana, Proc. Acad. Nat. Sci. Phil. 1854, vii. 

 p. 175 ; Stimpsoii, Crust. & Ecliin. P. S. N. Am. p. 49, pi. xxi. 

 tig. 4. 



Stimpson records the occurrence of this species at Fort Steila- 

 coom, Puget Sound (SucJdeT/), and near the mouth of San- 

 Francisco Bay ( Trask) . I have not been fortunate enough to 

 meet with it in the latter locality, but have found it in abun- 

 dance near Preston's Point, Tomales Bay. 



In the museum of the Cal. Acad. Sci. are several specimens 

 from Mutiny Bay, Alaska. 

 ■ Both the anterior feet of the female are of a bright rose 

 colour ; but the large hand of the male is nearly of the same 

 tint with the body. 



Upon specimens I collected in Tomales Bay were numerous 

 minute red parasites which I neglected to examine, but con- 

 jecture to have been Acarida. 



