1921 1 Schmitt: The Marine Decapod Crustacea of California) 87 



C. nigricauda, but longer and narrower; blade with anterior margin more advanced 

 at inner than at outer angle. Fifth segment of abdomen not carinate. 



Dimensions. — Type: from tip of antennal scale to tip of tail 63.5 mm., of 

 body from tip of rostrum 52.3 mm. The largest specimen taken in San Francisco 

 Bay, an ovigerous female, measured 69 mm. from tip of rostrum to end of telson; 

 the general average was between 40 and 45 mm. 



Color. — Readily distinguished from all others by the black spot on each side 

 of the tail (Lockington). 



Type Locality. — San Diego, California, 6 fathoms. 



Distribution. — From northern California to Lower California, 3 to 33 fathoms 

 (Eathbun). 



Biological Survey of San Francisco Bay. — Crago nigromaculata 

 is a bottom-dwelling form, rather scatteringly distributed in the mid- 

 dle and upper lower bay, and outside within the 30-fathom curve. 

 "With few exceptions all our specimens were taken on a muddy sand, 

 sandy mud, or mud bottom, in 5 to 16 fathoms by means of the sledge 

 trawl. Not a single specimen was taken in any of the tow-net hauls. 



In the middle bay out of a return of seventy-eight specimens from 

 thirteen stations (18% of the total number) only four hauls of one 

 specimen each were not made with the sledge trawl (D 5705, 5-foot 

 Tanner trawl ; D 5778 and 5779, 19-inch boat dredge and 3-foot Tan- 

 ner trawl, and D 5795, oyster dredge), and only three (D 5778, 5779, 

 5795 included in the four just mentioned) had a bottom of sand and 

 stones or boulders. These three were also the only middle bay records 

 not made in the upper and eastern portions of that division. Eighteen 

 specimens, all told, were obtained in two seine hauls on the Fort Baker 

 Beach. 



In the lower bay fourteen specimens were taken at three stations 

 (D 5803-5805; 8% of the total number), all of which were made 

 with the sledge trawl off Hunter's Point, on a soft mud bottom con- 

 taining worm tubes in two instances (D 5804, 5805). 



Outside at three stations (D 5736, 5792, 5806, 17% of the total 

 number), made with the 9 and 12-foot beam trawls in 9 to 26 fathoms, 

 on a fine gray to greenish sand bottom, twenty specimens were 

 obtained. 



The ranges of temperature and salinity correlated with the stations 

 from which this species is recorded are, respectively, 8.8° to 17.2°C, 

 and 27.8 to 34.1. 



The middle bay stations at which Crago nigromaculata was taken 

 are: D 5705, 5778, 5779, 5795, 5797, 5799, 5821, 5823-5826, 5828, 5830; 

 Fort Baker, April 19 and May 13, 1913. 



