42 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxvi. 



Thus, S. sanlucasij a form very rlose to S. fritsmuUeii, differs 

 from it in the shortness and more massive form of all its appendages. 



The frontal teeth are stronger, the rostrum, especially, being wider 

 at the base; the articles of the antennule are approximately equal, 

 and the proportion of total length to the width is only 4.25 instead 

 of 5, as in /S. fntzmillleii. 



The basicerite has its superior spine placed higher than in the pre- 

 ceding species, so that it reaches the extremity of the basal antennular 

 article, and makes the lateral spine short and stout. Although the 

 scale of the scaphocerite is as long as in S. fntzmulleri.^ the propor- 

 tion of its length to its width is only G instead of 6.6, on account of 

 its stoutness. The carpocerite is of the same form as- in the preced- 

 ing species, and also exceeds the antennule. 



The large chela has, for its relative dimensions, fingers 1, total 

 length 2.88, height 1.33 ; the small chela is lacking in the type. 



In the second pair the carpus is only 5.6 times longer than wide, 

 instead of 8, as in S. fiitzmuUeri; the relative proportions are: First 

 article of the carpus 1; sum of the four following ones 1.6; terminal 

 chela 1.72, very different, therefore, from the proportions found in 

 S. fritzmillleri ; the meropodite measures 0.7 of the length of the 

 carpus. 



The proportions of the third pair are: Meropodite 1.65; carpus 1; 

 propodite 1.56; the meropodite is only 2.53 times longer than wid'e. 



The dactyl has practically the same form as in *S'. fritzmillleri^ 

 the differences being that the ventral hook is wider at the base, and 

 the entire appendage is shorter than in the preceding species. 



The telson has not suffered the same diminution as the appendages, 

 the proportions of its length to its proximal and distal ends being 

 respectively 1.4 and 2.33, instead of 1.15 and 2, as in S. fj'itzmiilleri, 

 the telson of wdiich species is, therefore, wider and shorter. 



The eggs are of the same size as are those of the preceding species. 



/S. sanlueasi, readily distinguishable from the two American forms 

 /S. fritzmillleri and S. hemphilU, is much more closely allied to a 

 species which I collected at Djibouti, and to which I give the name 

 S. heroni, the species occuri'ing on the reefs of Pleron. S. heroni is 

 distinguished by the following points: The lateral spine of the 

 basicerite slightly exceeds the extremity of the median antennular 

 article, and the antennal scale is more reduced, the proportion of 

 its dimensions being about 7.3; on the other hand, its lateral spine, 

 as in the " oxyceros ^^ forms of many species, considerably exceeds 

 the carpocerite. 



The proportions of the large chela are: Fingers 1; length 3.2; 

 height 1.32, it being, therefore, less massive than that of S. san- 

 lucasi. 



i 



