""Tyor"'] PROCEKDINCJS OF Till-: NATIONAL MUSEUM. 77 



to the outer inaijL'iii, IVoiii wliicli [)oiiit a rowoflouj;- spines extends for- 

 ward alon.i; the lateral nuirgin and is coutinued on the pterygostomiau 

 regions. This marginal row of long spines, while fornn'ng the apparent 

 lateral margin, really overhangs and conee'.ils the real margin. This is 

 a eons])icuous difference between this species and opilioj in which the 

 branchial region is liattened out so that the posterolateral margin is 

 visible in a dorsal view to a point just back of the cheliped. From the 

 lateral row of long spines a small row of three or four spines extends 

 up on the carapace near the anterior part of the branchial region. 

 Small, sharp spines border the orbits, the outer margin of the i)ostocu- 

 lar teeth and the infero-lateral and posterior margins. 



The rostral liorns are longer and narrower than in opllio, leaving a 

 widely V-shaped notch between. 



The second segment of the abdomen of the male is bent (h)wnward 

 at the extremities in almost a right angle. There is a transverse ridge 

 of Pijiny tubercles on the sternum in front of the abdomen. Anterior 

 to this ridge the sternnm is dee])ly excavated. 



Tiie posterior margin of the epistome is strongly deflexed in tlie cen- 

 ter and arched at the sides. The external maxillipe<ls when in place 

 do not fit closely into the buccal cavity as in opilio; merus joints 

 strongly spinose on the margins. On removing the carapace from 

 specimens of tanneri and opilio of equal size, the gills in tlie former are 

 seen to be much larger than in the latter, being about two^fifths longer in 

 tanneri. There are corresponding differences in the niaxilli[)eds. The 

 scaphognathite of the second maxilla is very much larger (pi. iv, figs. 

 2 and 5), and also the endoi)odite of the first maxilliped (figs. 3 and G). 

 The foliaceous part of the flabellum has about twice the area of the 

 same in oiriHo (figs. 4 and 7). 



The legs are armed with spines longer and stouter than tliose of 

 opilio. In adnlt specimens the ambulatory legs are longer than in 

 opilio, especially the merus joints, which arc much narrower and in the 

 males do not Aviden ont at the proximal end as in oirilio. The ambula- 

 tory legs of the female are shorter than those of the male, as is the case 

 in opilio. In comparing young specimens of both s])ecies tlie difierence 

 in the length of the ambulatory legs and in the width of the merus 

 joints is not evident. 



