218 BRITISH PARASITIC COPEPODA. 



4. Clavella emarginata Kroyer. 

 (Plate LXIX, fig. 7 ; Plate LXVI, fig. 17-20.) 



1837. Anchorella emarginata Kroyer. (70) pL i, voL i, p. 287, pi. iii, fig. vi. 

 1851. Anchorella emarginata P. J. van Beneden. (11) p. 113, pi. vi, fig. 4. 

 1877. Anchorella emarginata Kurz. (71a) Zeitschr. f. wiss. Zool., voL 

 xxix, p. 398. pi. xxv, fig. 8. 



1900. Anchorella emarginata T. Scott. (112) p. 176, pi. viii, figs. 49-51. 

 1906. Clavella emarginata Brian. (21) p. 109, pi. x, fig. 3. 



Female. Cephalothorax very long and slender, 

 twice as long as the genital segment ; head small and 

 separated from the long neck by a slight constriction. 

 Genital segment subquadriform, considerably dilated, 

 and somewhat truncated at the posterior end. Ab- 

 domen obsolete or nearly so. Egg-strings short and 

 tolerably thick. 



Antennules short, composed of three articulations. 

 Mandibles small and armed with only moderately 

 large teeth ; maxillae narrow, provided with three 

 apical spines and with two small ones on a rudimen- 

 tary branch near the middle of the joint. First maxil- 

 lipeds moderately small and uncinate. Second maxil- 

 lipeds moderately thick, very short, and not completely 

 united except at the tip, where they are joined together 

 to a chitinous plug. Length. The specimen repre- 

 sented by the drawing measures, exclusive of the 

 cephalothorax, about 2*5 mm., while the cephalo- 

 thorax alone measures 3 '5 mm. 



We have not seen the male of this species. 



Habitat. Parasitic on the gill-arches of the allis 

 shad (Clupea alosa) and of the twaite shad (Clupea 

 finta}. Plymouth on Clupea (Bassett- Smith). Dun bar, 

 Firth of Forth, on Clupea finta (T. Scott). 



This species is readily distinguished by the long, slender 

 cephalothorax, the dilated genital segment, and by the 

 imperfectly united second maxillipeds. 



5. Clavella scombri Kurz. 

 (Plate LXVII, figs. 1-3 ; Plate LXVIII, figs. 1-7.) 



1877. Anchorella scombri Knrz. (71a) Op. cit., p. 403, pi. xxv, figs. 12, 

 35. 41. 



