50 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxvi. 



male and female are very slight ; the frontal teeth are very short, and 

 the rostrum a little shorter and weaker than the lateral teeth, espe- 

 cially in the male. In both cases the antennule is 5.5 times as long as 

 wide; the lateral spine of the scaphocerite is as long as the antennule; 

 the carpocerite exceeds it xerj little in the female, a little more in the 

 male, and is very njuch swollen, only 3.5 times as long as wide in the 

 male, or 3.3 times in the female ; the meropodite of the third pair is 

 3.25 times as long as wide in both specimens. 



This form of S. dig net i (which might be distinguished under the 

 name of ecuadorensis) makes the distribution of the Brevicarpus 

 group nuich like that of the Paulsoni group, Avhich has representa- 

 tives in Lower California and Chile, in Brazil and Florida, as well as 

 in the West Indies. I have shown in the introduction to this paper 

 what interest attaches to the presence or absence of the species of the 

 Brevicarpus group elsewhere than on the American coasts, because of 

 their close relations of kinship with the species of the Paulsoni 

 group. 



St. Helena, Ecuador; ^M. Festa; 12 specimens, male and female 

 (Paris Museum). 



Named for M. Diguet. 



SYNALPHEUS BREVICARPUS (Herrick). 



Alpheus mulcyi var. brcricariuis Herkick, Mem. Nat. Acad. Sci., V, 1891, 

 p. 383. 



The species is also very like S. minus, from which it is distinguished 

 by the following characters : 



The proportions of the antennular articles are 1.8, 1.7, 1 ; the pro- 

 portion of the length to the width of the antennule is at least 5.5. 



The basicerite is not spinous above; it bears an angular prominence, 

 at most as long as wide at base. 



The scaphocerite has a very wide scale, Avith the border regularly 

 curved within; it is from 5.5 to G.4 times longer than wide; the hairs 

 which border it are at least twice as long as those in S. nun us: but, on 

 the other hand, the lateral spine, shorter and more obtuse, does not I 

 reach the end of the antennular stalk. 



The carpocerite is sensibly 4 times as long as wide and more cylin- 

 drical than in S. minus. 



The large chela has the following relative dimensions: Fingers 1; 

 total length 3; height about 1.15, varying to 1.2. In the large speci- 

 mens the movable finger presents a second obtuse prominence between 

 the point and the molar processes of the lower margin ; the palm is less 

 regularly ovoid than in S. minvs, and more tapering on the proximal | 

 side. 



The small chela measures a third of the preceding; the relative 

 dimensions are : Fingers 1 ; total length 2.35 to 2.4 ; height 0.65 to 



