LEPEOPHTHEIRUS OBSCURUS. 71 



has a branched furcula, but the former was taken on 

 the brill, while the latter was found on Raid clavata." 

 A LepeophtheiriM found on the brill by T. Scott, and 

 doubtfully ascribed by him to L. obscuras Baird, seems 

 to be merely a form of L. thompsoni, not deserving- 

 even varietal rank. Bassett-Smith's L. obscurus is 

 probably similar, for in a copy of the ' Ann. and Mag.' 

 paper referred to above kindly presented by the author, 

 the lunulge shown in figure 2, Plate 4, are deleted and 

 the words " no lunulas " are added at the side ; so also 

 the bifurcate appearance of the rami of the sternal 

 fork shown in figure F on the same plate may like- 

 wise be due to an inadvertence.] 



5. Lepeophtheirus salmonis (Kroyer). 

 (Plate XVII, fig. 4; Plate XVIII, figs. 11, 12.) 



1837-38. Caligus salmonis Kroyer. (70) vol. i. pi. vi, fig. 7 a-c ; vol. ii. 

 pp. 13-18. 



1850. Lepeoplitheirus stromii Baird. (4) p. 274. pi. xxxii, figs. 8, 9. 



1863. Lepeophtheirus salmon i* Kroyer. (71) p. 211, pi. xvii, figs. 1 a, I. 



1900. Lepeophtheirus stromi T. Scott. (112) p. 152, pi. vi, figs. 3-8. 



1905. Lepeophtheirus salmonis C. B. Wilson. (145) p. 640, pi. xxiv. 

 figs. 294-300. 



Female. Carapace rather longer than broad, and 

 equal to about three-sevenths of the entire length of 

 the animal, lateral margins slightly and evenly arcuate. 

 Frontal plates not very clearly defined, the margin 

 convex, and without lunulae. Free thoracic segment 

 very small. Genital segment tolerably large and of 

 an oblong form, rather longer than broad, its length 

 being about a third less than that of the carapace, the 

 lateral margins only slightly arcuate but the postero- 

 lateral corners produced into rounded lobes, with the 

 space between them deeply incurved. Abdomen 

 narrow, elongated and un segmented, and equal to 

 about one-fourth of the entire length of the animal ; 

 distal end slightly constricted so as to have the appear- 

 ance of an indistinct joint. Caudal rami very short. 



Antennules rather small. Antennas tolerably robust, 

 and furnished with a moderately strong terminal hook. 



