, NO. 1573. PARASITIC COFEPODS— WILSON. 479 



Abdomen the saine shape as in the female, bnt more of it visible 

 behind the genital segment; anal laminae narrower and smaller than 

 in the other sex, each armed with three good-sized setae. 



First antennsB relatively longer than in the female; second pair 

 also enlarged, their terminal claws projecting well in front of the 

 carapace. Other appendages similar to those of the female, except 

 that on all of them the claws and spines are longer and sharper. 



{Phil(>rtJi mgoriscus , (pikeco^ to love, and Orthragoriscus , the old gen- 

 eric name of its host.) 



In 1863 Kroyer described a new species, which he referred to the 

 genus Dinematura and called D. serrata. The present author obtained 

 numerous specimens of both sexes of this species while at Woods 

 Hole in 1904. On examination it was found that they could not 

 belong to the genus Dinematura for the following reasons: First the 

 general body make-up is entirely different ; the body is too short ; the 

 genital segment is not elongated enough; the dorsal plates of the 

 fourth segment are many times too large ; the abdomen is much too 

 large and in the wrong position. Again, there is no trace in the present 

 species of the adhesion disks found on the ventral surface in Dineina- 

 tura. In the third place there is no trace here of that sixth segment 

 which is the characteristic of Dinematura, with its rudimentary legs 

 and dorsal plate. And finally in Dinematura all the legs are bira- 

 mose, the rami of the first pair are two-jointed, those of the second 

 and tliird pairs three-jointed, wliile the rami of the fourth pair are 

 enlarged into laminae in which there is almost no trace of jointing. 

 Here the rami of the first three pairs are two-jointed, while those of 

 the fourth pair are rudimentary, very nuich reduced in size, and one- 

 jointed. 



Accordingly a new generic name was given to the species, but for- 

 tunately the author afterwards found Horst's paper (1S97), in which 

 he had already renamed the species as given above. 



Kroyer and Horst are the only two who have ever described tlie 

 species. Kroyer had no specimens of the male sex and Horst had but 

 a single one, of which he gives only one small figure, a dorsal view. 



For this reason the male has been fully described and figured in the 

 following account : 



PHILORTHRAGORISCUS SERRATUS Kroyer. 



Plates XLII and XLIII. 



Dinematura serrata Kroyek, 1863, p. 176, pi. viir, figs. 4 a to i. 

 Philorthragoriscus seiratus Horst, 1897, p. 137, pi. vii. 



Female. — Carapace well rounded, about one-sixth wider than long, 

 with large acuminate teeth along the lateral and posterior margins. 

 Frontal plates wide and fairly distinct; but still fused with the carapace; 



