78 Mr. P. W. Bassett-Smith on 



have been described. I have therefore in this paper brought 

 forward a few more of the best-marked forms, following 

 " Gerstaecker's " classification, as before, having, however, to 

 add to his genera a new one in the family Dichelesthiina. 



It is very pleasing to be able to bring to light second 

 species of two genera, both of which were created by 

 l3r. Heller in 1865, my specimens having been obtained in 

 localities considerably removed from that whence the original 

 ones came ; in the case oi Nermilius, tliough the species differ, 

 the genus of both host and parasite remains constant. 



At present there are a large number of known species 

 belonging to the genus Cah'gus, some of which have been 

 described from single specimens, or even from the male alone; 

 this should evidently be avoided as much as possible, for in 

 different stages of growth they vary considerably in outward 

 conformation, especially with regard to the shape of the 

 genital segment ; true differentiation can only be carried out 

 by detailed examination of the articulate organs, maxillary 

 and swimming-feet, &c. Since describing C. hirsutus * 

 many larger specimens of this species have been taken ; in 

 these the genital segment became broader and more winged, 

 but the characteristic condition of the fourth pereeopods is 

 always present, as also the dilated appearance of the abdo- 

 minal portion. 



The work of collecting is difficult, for in a native market 

 the crowds of moving, gesticulating, dirty, odoriferous men 

 and women, though picturesque, render close inspection 

 and examination of the fish almost impossible, besides the 

 dislike the natives mostlj^ have of a " saheb " touching any- 

 thing they may want to eat; again, no doubt a large number 

 of those parasites that live on the external surface get washed 

 off before the fish are taken to the market. 



Ergasilidse. 



BOMOLOCHUS, Nordm. 

 Bomolochus denticulatus, sp. n. (PL III. fig. 1.) 



A series of specimens of this species were taken in small 

 numbers at a time from the gill-cavities of a " Barracouda " 

 {Spltyrcena jello) from Trincomalee and Colombo, as well as 

 from the gills of a "garfish" {Hemirhamphus far), also at 

 Trincomalee, often together with a small Caligus not yet 

 described. 



* Ann. & Mag. Nat. Hist., Jan. 1898, p. 6. 



