DECAPOD CRUSTACEANS OF THE BEAXJFORT, N. C, REGION. 381 



Family SERGESTIDAE. 



Peneidea having the last two pairs of legs reduced in size or lost and the gills few 



or wanting. 



Three genera are recognized, of which only the following is known from the Beaufort 



region. 



Genus LEUCIFER Milne-Edwards (=LUCIFER of most authors.). 



Leacifer Milne-Edwards, 1837, p. 468. 



Leucifer fazoni Borradaile. PI. xxvi, fig. 10. 



Lucifer typus. Faxon, 1879, p. 113, pi. 7, figs. 1-3. 

 Lucifer sp. Brooks. 1883, pp. 57-137. 

 Lwo/er /axcmi Borradaile, 1915, p. 228. 



Integument smooth, thin, and transparent. Anterior portion of cephalothorax greatly lengthened, 

 bearing the eyes, antennules, and antennae far in front of the mouthparts and legs; abdomen strongly 

 developed, with large swimmerets and tail fin. 



Anterior prolongation of cephalothorax about one and one-half times as long as posterior portion, 

 nearly cylindrical, produced into a small rostrum, a spine on each side behind the eye, and a knoblike 

 suborbital lobe. Posterior portion of cephalothorax with a small spine on each side in front. Eyes 

 large and prominent, on stout conical stalks about one-third the length of the anterior part of the cephalo- 

 thorax. Peduncle of antennules long and slender; basal article longer than the other two combined; 

 third article shortest; flagella long and slender. Peduncle of antennae about half as long as first article 

 of the antennular peduncle; flagellum slender, 

 longer than that of the antennule; scale almost 

 linear and fringed along its inner margin with long 

 hairs. Mandibles without a palpus. Twopairsof 

 maxillae and three pairs of maxillipeds, the last 

 pair pediform, are present. Four pairs of slender 

 legs, the first two pairs short, the last two of nearly Fro. ^.-Leucifer faxoni. d'.X lo. 



equal length and extending forward almost to the 



end of the cephalothorax. Abdomen much compressed, its segments deepest at the point of insertion of 

 the swimmerets and there produced into a spiniform angle ; sixth segment as long as the two which precede 

 it, its posterolateral angles spiniform, a small median spine above the base of the telson and, in the male, 

 two strong lateral spines of which the posterior is curved and about twice as long as the anterior. Telson 

 slender, about half as long as uropods, with a stout spine on each side and a prominent projection on the 

 ventral side near the middle. Uropods about as long as the sixth segment, the outer branch strongly 

 developed, the inner branch much shorter and narrower. 



Length, lo to 12 mm. 



Color, when alive, almost perfectly transparent; in alcohol, white. 



This interesting little shrimp is not uncommon in the waters of the harbor and has been taken in 

 the tow nets throughout the summer. Egg-bearing females were collected June 30, 1912. Outside 

 the harbor it is much more abundant, at times occurring in such great swarms that it constitutes a large 

 proportion of the plankton material. 



The development of Leucifer was worked out by Dr. W. K. Brooks from material secured, largely, 

 at least, at Beaufort, and his paper, already cited, is a zoological classic. His figures of the animal are 

 the best that have been published and show conclusively that he was dealing with the species that is 

 described above. Unfortunately in this, as in many other cases. Dr. Brooks made no effort to determine 

 the proper specific name of his specimens. Faxon's description and figures show that he also was 

 dealing with the present species to which, with some doubt, he applied the name Lucifer typus 

 Milne-Edwards. In a recent paper, however, Borradaile shows that the Leucifer of the western Atlantic 

 is not L. typus or any other hitherto described species, and proposes for it the name L.faxoni. 



It was the opinion of Dr. Brooks that Leucifer breeds in the marshes which border the harbor along 

 the town front. His reasons for coming to such a conclusion are not altogether satisfactory, and in view 

 of the fact that the shrimp is far more abundant outside than inside the harbor and that the genus is 

 known the world over as a strictly pelagic one, it is very probable that he was mistaken. 

 69571°— 18 25 



