NO. 1659. AMERICAN SPECIES OF 8YNALPHEUS—C0UTIERE. Q^ 



rudiment to a scale reaching the proximal third of the median anten- 

 nular article; its lateral spine, wider than that of the basicerite, 

 hardl}^ reaches be\'ond the middle of the distal antennular article; 

 the carpocerite exceeds the antennule by one-half of the distal article, 

 and is G times longer than wide. 



The ^proportions of the large chela, in the male, are: Fingers 1; 

 total length 8.4; height 1.35; the anterior margin of the palm bears 

 a tubercle which terminates in a horizontal spine; the meropodite is 

 rounded and unarmed on its superior margin; the proportions are 

 the same in tlie female, but the palm is more tapering anteriorly. 



The proportions of the small chela are: Fingers 1; total length 

 2.8 ; height 1 : the carpus measures only 0.35 of the entire chela ; 

 the meropodite is 3.3 times as long as wide: the fingers terminate 

 in a single point ; the plume of hairs of the movable finger is less 

 thick than in S. grampusi. In the female the small chela is only 

 slightly narrower, the proportions being 1, 2.8, 0.92; the meropodite, 

 with the same proportions, is also a little more slender. 



In the second pair, in both sexes, the first segment of the carpus, 

 the sum of the four following ones, and the distal chela, are nearly 

 equal, but progressively diminish slightly in length; the carpus is 

 10 times longer than wide. 



The proportions of the third pair are: Meropodite 2; carpus 1; 

 propodite 1.6; the meropodite is 3.5 times longer than wide; the 

 dactyl is short, terminating in two equal and slightly divergent 

 hooks. 



In the female the proportions are approximately the same; the 

 height of the telson is 1.25 times its base and 3.6 times its posterior 

 margin, which bears two pairs of feeble spines, the inner ones 

 slightly the longer : betw^een these are ten plumose hairs. 



The external uropod bears only two feeble teeth, with a movable 

 spine between them. 



The eggs give rise to zoea^. 



SYNALPHEUS PANDIONIS, new species. 



This species is distinguished from S. grampusi only by very slight 

 differences, of which the principal one is the presence of a Avell- 

 developed antennal scale. It is also very like S. parfaiti^ which it 

 approaches especially in this last character. However, I believe that 

 these three forms are perfectly distinct. They appear to be the 

 result of different types of variation. 



The frontal teeth resemble those of S. parfaiti^ but this is not true 

 of the stylocerite, which is always markedly shorter than the distal 

 article of the antennule, as in S. grampusi: the superior angle of 

 the basicerite is obtuse, its lateral spine reaching the extremity of 

 the median antennular article; the scaphocerite has in both sexes a 

 very distinct scale, which reaches the middle of the median anten- 



