C A R I D E A. 



597 



produced backward into a long spine on the dorsum, a peculiarity 

 which suggested the name Oplophorus, given by Edwards. Eegulus 

 differs from Oplophorus in having no palpi to the legs, and also, in 

 having no chelae to the anterior feet. 



The species are nearly transparent, and live in the open ocean. 



Genus REGULUS, Dana. 



Corpus vix compressum. Rostrum elongatum, dentatum. tegmentum 

 abdominis Stium dor so postice instar spinas productum. Squama 

 antennarum acuminata, extus pauci-dentata. Pedes non palpigeri; 

 antici graciles, parvi, articulo ultimo styliformi; 2di crasse chelati; 

 Stii 4-ti 6tique longi, graciles. Antennas internal Jkigellis duobus con- 

 fectce. 



Body hardly compressed. Beak elongate, dentate. Third segment 

 of abdomen produced behind on the back into a spine. Basal scale 

 of outer antennae few-toothed on outer margin. Feet without 

 palpi ; first pair small and slender, last joint styliform ; second pair 

 stout chelate ; third, fourth, and fifth pairs long and slender. 



The animal in swimming shows only its three posterior pairs of legs 

 (as in fig. 5, pi. 39), the anterior being thrown forward directly under 

 the body. The beak is broad as it approaches its base, and forms an 

 arched cavity over the eyes. The abdominal segments are more or 

 less pointed at the lateral margin, and also ciliate. The two pro- 

 cesses of the mandible are quite narrow ; the palpus is three-jointed 

 and rather long, the joints nearly equal. The second pair of maxil- 

 lipeds has the terminal segment at the lower extremity of the pre- 

 ceding. The outer pair is slender and long (exceeding the first pair 

 of feet in length) ; the third joint is not half as long as the following, 

 and this, the last, is subterete and acuminate; the palpus is a little 

 longer than the second joint. The hands in both species have the 

 fingers short and gaping. The fifth pair of legs is shorter than either 

 of the two preceding. 



Both species also have a supra-orbital tooth, which is situated at 

 the termination of the lateral margin of the beak. 



150 



