56 



PROCEEDINGS OF THE NATlOyAL MtJBEVM. vol. xxxvi. 



female the large base is double the small. The posterior margin bears 

 4 spines, the inner a little longer, Avitli 4 long plumose hairs between 

 them, and 3 pairs of simple hairs inserted above the preceding. The 

 uro^Dods are larger in the male, the outer especially; the latter bears 

 on its outer margin above the transverse suture a series of 7 to 8 teeth 

 and a movable spine between the first two. 



The eggs are of small size and the larvas are zoese. The species 

 may be found in sponges, but it is not probable that such is its normal 

 habitat. 



I have been able to sepai-ate among the young males a rather large 

 number of specimens diU'erent from the type and different also from 



the following species, S. 



(/oodei, with which, how- 

 ever, they agree in hav- 

 ing a well-developed an- 

 tennal scale. Compared 

 to young male longicar- 

 pus of the same size, they 

 are distinguished — 



(1) By the antennal 

 scale reaching the ex- 

 tremity of the second ar- 

 ticle of the antennule; 



(2) by the carjjocerite a 

 little thicker (propor- 

 ti(ms: 1:4.6, 4.9 or 5, in- 

 stead of 1 : 5.5 or 5.6) ; 



(3) by the large chela in 

 which the anterior border 

 of the palm ends in an 

 obtuse point, conical and 

 strong; (4) by the telson 

 a little narrower at the 

 base; this is contained 1.8 

 times in the height in- 

 stead of 1.4 times. 



Excepting in the form and size of the antennal scale, which are 

 quite similar, these specimens are also shown to be very distinct from 

 the males of S. goodei of the same size — 



(1) By the carpocerite a little thicker (the same difference as 

 with S. longicarpus) ; (2) by the large chela, invariably shorter and 

 thicker in S. goodcl^ even in the young, not exceeding 12 mm. in length 

 (proportion of thickness 1.1) ; (3) by the small chela, of which the 

 carpus and the palm are shorter in S. goodei; their sum equals only 

 4 times the height of the palm instead of 5 times, as in the specimens 



Fig. 32. — Synalpheu.s longicarpus approxima. n, 



FRONTAL AND ANTENNAL REGION ; C, CARPOCERITE ; 

 K, LARGE chela; Ic' , SMALL CHELIPED OF FIRST 

 PAIR OF A YOUNG SPECIMEN ; Ick' , SMALL CHELIPED 

 OP FIRST PAIR OF AN ADULT; m, MEROPODITE OF 

 THIRD FOOT ; t, TELSON. 



