CHONDRACANTHUS ZEI. 179 



and Clyde (T. Scott). Irish Sea (A. Scott). This 

 parasite is of frequent occurrence on the dory, and 

 Dr. Bassett- Smith describes it as very common on the 

 gills of Zeus fab er at Plymouth. 



The ovisacs of Chondracanthus zei differ so remarkably 

 from those common to most of the species known to us that 

 we give here a figure showing a side and an end view, 

 enlarged, of one of them. When the parasite is viewed from 

 the ventral aspect the ovisacs appear as in figure b, but the 

 side view a can best be seen whem the ovisacs are removed. 

 x shows the point of attachment of the ovisac to the genital 

 segment. 



10. Chondracanthus lophii Johnston. 

 (Plate LII, fig. 4; Plate LVI, figs. 16-18.) 



1836. Chondracanthus lophii Johnston. (67) p. 81, fig. 16. 

 1837-1838. Chondracanthus gibbosus Krbyer. (70) (1) p. 252, pi. ii, 

 fig. 4. 



1843. Chondracanthus lophii Ratlike. (100) p. 116, pi. v, figs. 16-1S. 

 1847. Chondracanthus gibbosus Thompson. (129) p. 248. 



1850. Lementoma lophii Baird. (4) p. 330, pi. xxxv, fig. 3. 



1851. Chondracanthus gibbosus P. J. van Beneden. (11) p. 104, pi. iii, 

 figs. 10-15. 



1862. Chondracanthus lophii Turner & Wilson. (140) p. 67, pi. iii. 

 1877. Chondracantlms gibbosus Vogt. (142) p. 76, pi. v, figs. 1-4 ; pi. 

 vi, figs. 1-3. 



1896. Chondracanthus lophii Bassett-Smith. (7) p. 162. 

 1900. Chondracanthus lophii T. Scott. (112) p. 167. 



Female. — Body tolerably elongated, narrow in front, 

 posterior end moderately broad and flattened. Head 

 small, having on each side a horn-shaped appendage 

 directed obliquely backwards. Thorax narrow and 

 furnished with one or two short, paired, marginal 

 processes directed outwards, and a pair of bifurcated 

 moderately long ventral appendages. Genital seg- 

 ment flattened, and about twice as long as broad, 

 constricted in the middle so as to form two subequal 

 portions, the postero-lateral corners of both of which 

 form short prolongations ; this segment also furnished 

 with a row of median digitiform processes alternately 

 larger and smaller, and directed obliqueby backwards. 

 Abdomen very short. Egg-strings greatly elongated 

 and more or less twisted into loops. 



