COPEPODS OF THE WOODS HOLE REGION 501 



3. Second thoracic segment narrowed anteriorly ; swimming legs 



with short, knoblike lobes, which are smooth flurae (p. 502) 



Second thoracic segment not narrowed anteriorly ; swimming legs 



deeply lobed and covered with spinules depressa (p. 503) 



4. Head ovate, narrowed anteriorly ; swimming legs with very short 



and blunt lobes; fourth segment shorter than third phycidis (p. 504) 



Head obovate, narrowed posteriorly ; swimming legs with long 



and acuminate lobes; fourth segment longer galerita (p. 505) 



ACANTHOCHONDRIA EXILIPES, new species 



Plate 37, a-e 



Occurrence. — A female with attached male was taken from the 

 gills of the tile fish {Lopholatilus chamaeleonticeps) by M. T. Thomp- 

 son in July, 1914, and is made the holotype of the new species 

 with U.S.N.M. No. 59777, The fish was captured on the continental 

 slope south of Woods Hole. From the same host and locality 

 Rathbun secured six specimens in August, 1881, and a little farther 

 east Vinal Edwards obtained 40 specimens in July, 1902. 



Color (preserved material) . — Body a uniform brownish yellow. 



Female. — Head elliptical, longer than wide, narrowed anteriorly 

 and slightly widened across the posterior margin, which is squarely 

 truncated. Carapace covering the entire dorsal surface, split length- 

 wise on the midline nearly to the posterior margin. First two 

 metasome segments free, the first slightly wider than the head and 

 the second a little wider than the first. The legs usually extend 

 out laterally so as to become more or less visible in dorsal view. 

 Last three metasome segments fused, the division between the third 

 and fourth segments indicated by a fairly distinct dorsal groove, 

 that between the fourth and fifth segments merely indicated by 

 lateral indentations. Fifth segment produced posteriorly into a 

 conical process at each corner ; these processes taper to a blunt point, 

 curve inward so that their tips nearly come together, and are longer 

 than the combined fourth and fifth segments, reaching half their 

 length beyond the tip of the abdomen. Genital segment small, 

 about as wide as long ; abdomen made up of a single segment swollen 

 into a sphere nearly as wide as the genital segment and bearing on 

 its ventral surface near the base of the segment a pair of conical 

 caudal rami, each armed with a single lateral seta. 



First antenna narrow cylindrical', the jointing so indistinct that it 

 appears 1-segmented, and tipped with a tuft of small setae. Second 

 antenna with a short and broad basal segment and a stout apical 

 claw, curved into a semicircle. Mandibles sickle-shaped, the teeth 

 on the posterior margin larger than usual and slightly separated 

 from one another. First maxilla made up of a single stout seg- 

 ment tipped with two setae and without a palp ; second maxilla with 

 a subquadrate basal segment and a short apical cl'aw toothed along 



