NO. 1659. AMERICAN SPECIES OF SYNALPHEUS—COUTIERE. 



33 



The small chela is one-third as lon<>: as the large one; its relative 

 dimensions are: Fingers 1; total length 2.5; height 0.8 or a little less. 

 The meropodite is 3.1 times longer 

 than wide; its upper margin ending 

 in a sharp angle. 



In the second pair, Avhich is slender 

 and elongate, the first article of the 

 carpus measures 1, the sum of the four 

 following is 0.83, and the chela 0.75. 

 The relative dimensions of the third 

 pair are: Meropodite 2.41 (five times 

 longer than wide) ; carpus 1 ; pro- 

 podite about 2.14, the foot as a whole 

 being long and slender, especially the 

 propodite ; the dactyl is also elongate, 

 its ventral hook less thick and espe- 

 cially much shorter (about one-third) 

 than the dorsal, with which it is 

 parallel in direction. 



The telson has sharp posterior an- 

 gles, with the inner pair of spines very slender, three times longer than 

 the outer pair; the convex posterior border has twelve plumose hairs. 



The eggs should give, in acordance 

 with their size, zoea larva?. 



This species represents on the Amer- 

 ican coasts S. hastiUcrassus of the Lac- 

 cadives and Maldives. The latter is 

 distinguished by the large cheliped, in 

 which neither the palm nor the mero- 

 podite is spinous, by the shorter dactyls 

 of the thoracic feet, in which the ven- 

 tral hook is the more important, by the 

 telson having more pronounced angles, 

 and the inner spines shorter than in 

 S. townsendi. The carpocerite is also 



Fig. 16. — Synalpheus townsendi 

 brevispinis. a, frontal and an- 

 tennal region ; c, carpocerite ; k, 

 large ch,ela ; m' , dactyl of third 



PAIR ; t, TELSON. 



more 



swollen than in the last-named 



species. 



S. townsendi shows some interesting 

 variations. In a male specimen from 

 Albatross Station No. 2406 (form pro- 

 ductus) the rostrum and the frontal 

 spines are very elongate, as is also the 

 lateral spine of the scaphocerite. This 

 " oxyceros " form ( very frequent in 

 Synalpheus), is seen likewise in the Maldivian species, S. hastiUcras- 

 sus, at least as to the elongation of the rostrum. 

 Proc. N. M. vol. xxxvi — 09 3 



Fig. 17. — Synalpheus townsendi 

 mbxicands. a, frontal and an- 

 tennal region ; m', dactyl of 



THIRD PAIR ; t, telson. 



