^'mJ''] PROCEEDINGS OF THE NATIONAL MUSEUM. 235 



Length 10, width l.'>, leiigtli of clicliped about L'5 millimeters. 



Off San Domiu.i^o Pc.iiit, Tiower California, lat. L'do 07' N., long. 113° 

 32' W., 74 fatlioiiis, line, gi'ay sand, temperature ^o"^, station 3043, U. 

 S. Fish Commission steamer Albatross, 1889; one male (173C5). 



Mesorhoea gilli. 



Carapace much l)roader than long. Surface minutely pubescent. Ele- 

 vations of cardiac, gastri<', and branchial regions angular, each pro- 

 longed in a three-sided sjjine, that on the In-anchial ri^gion situated on 

 the ])ostero-lateral margin. The angles or ridg(\s are more or less cren- 

 uhite or tuberculate. The two gastiic ridges grsidually di\ crge from the 

 spine and arc^ continued nearly to the front. Tlie cardiac spine is longer 

 than the others, com])ressed laterally so that its anterior face is narrower 

 than its lateial lat;es. The branchial lidge is curved, subjiarallel to the 

 anterolateral margin ami has a tubercle in the center larger than the 

 others. In front oi" the branchial ri«lge are a few scattered tubercles: and 

 there are one(n'twotul)ei'clcs on thehe])atic region. Behind the branchial 

 ridge tin* surface is concave with the exception of the median spines. 

 Eostrum very short, ])ubescent. Anterolateral margin convex, dis- 

 tinctly crenulate; jiostero lateral and ])osterior margins (Mitire, thin, 

 with faint imi)ressed lines indicating the normal crenulation. Tostero- 

 lateral margin concave;, ahout twice as long as the ])osterior nuirgin, 

 which is slightly convex in the middle, terminating in a triangular flat- 

 tened spine at either angle, liidge lietwcen the subhejtatic and afferent 

 channels miiuitely crenulate, pubescent, continued on the subbianchial 

 region with several l)ea(l like tubercles. Suborbital tooth strongly 

 ridged. Male abdomen with first segment very sliort; second, Avidest 

 with a transverse denticulate crest, having a larger denticle at the ex- 

 tremities ami in the middle; third, fourth, and filth S(>gmeuts auchy- 

 losed; sixth, wid<'r than long; seventh, very short, triangular. Abdo- 

 men and sternum smooth. Female abdonu^n with seven segments; 

 first segment in large si)ecimen almost concealed under the carapace; 

 second, with transverse denticulate crest; third, with a similar faint 

 crest not <;ontinucd to the margins. Hasal aiitcnnal Joint w itli a long 

 trigonal spine below, [schinm of external maxillipeds punctate, outer 

 margin pubescent, inner maigin crenulate; merus with surface uneven, 

 l)ubescent, anterior nnirgin c(Uicave; a groove runs diagonally forward 

 and outward across the surface; tlu're are two tubercles on the outer 

 side of this gr(R)\e, one of which is at the antero exlcrioi' angie; the 

 inner angle is strongly i)ro(lu<;ed and bears a. granulate ridge. Chel- 

 il)eds h»ng and stiong; uhmus trigonal, with margins irregularly den- 

 tate or crenulate; ('arjius morc^ or less four-sided, margins fiiu'ly den- 

 ticulate or crenulate, a ridge running across 'the low<'i' surface; hand 

 long, trigonal, pidx'scent, up])er surface slightly twiste<l, about ten 

 teeth on the inner margin and thirteen smaller teeth on the outer mar- 

 gin, lower margin ten toothed; (la<;tyl at right angles to the upper sur- 



