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PROCEEDINGS OF THE NATIONAL MUSEUM. 



acutely dentate as in astroides, are thick, and the posterior margin is 

 bordered by small but prominent lobes. This margin is almost trans- 

 verse, the posterior border of the branchial expansion not being 

 Inclined forward as in astroides. The lateral margin of the branchial 

 region is much longer than in astroides, and the hepatic region is much 

 more x)rominent. The general elevations and depressions of the cara- 

 pace are similar to those of astroides. The surface is covered with 

 small irregular pits, separated by low, smooth, reticulating ridges. 

 The higher portions of the carapace bear at intervals tubercles covered 

 with depressed granules. Under the lens the entire surface is seen to 

 be densely and finely punctate. 



The merus of the chelipeds is less thick than in astroides, and is 

 armed with blunt tubercles or spines, as follows: A large tubercle on 

 the distal third of the posterior margin; three or four rather slender 

 blunt spines on the proximal half of the same margin ; three prominent 

 tubercles on the proximal half of the anterior margin; three low tuber- 

 cles on the inferior margin ; one tubercle on the superior surface. The 

 hands are broader than in astroides, and broader at the base of the lin- 

 gers than elsewhere, the upper margin of the outer surface being con- 

 cave. The fingers are thick, especially the poUex. The armature is 

 less striking than in astroides ; instead of the elongated spines in that 

 species, there are triangular, acute, and spinulous teeth. Of these 

 there are five or six on the lower margin of the propodus, three being 

 on the pollex; they are directed obliquely inward. The upper surface 

 is deeply concave, and is bordered inwardly by three teeth, the median 

 large and rounded. Dactylus with three small spines on the superior 

 border of the inner surface. The surface of the chelipeds is similar to 

 that of the carapace, except that the hands are rougher and more 

 spinulous. The meral joints of the ambulatory legs are bordered by 

 spinulous lobes or teeth; the propodi and dactyli are covered with 

 spiuules; surface of meri and carpi relatively smooth. 



JJimenaionn of three specimens of Thyrolambrus erosua from station 2829. 



Types. — No. 21577, U.S.N.M. Two males, two females, from off Cape 

 St. Lucas, 31 fathoms, station 2829. 



Distribution. — Southern part of Gulf of California and off Cape St. 

 Lucas, 8 to 31 fathoms, stations 2824, 2828, 2829. 



