CHONDRACANTHUS NODOSUS. 177 



which, though resembling the adult in having the 

 lateral margins coarsely crenulated, differs in being 

 proportionally narrower and in the more quad- 

 rangular form of the cephalon. 



Male. The male is very small, the length being 

 rather more than half a millimetre. The cephalo- 

 thorax is considerably enlarged, and the abdomen 

 short and indistinctly segmented. In size and struc- 

 ture the male closely resembles the male of Chondra- 

 canthus cornutus except that the structure of the 

 thoracic part is slightly different. 



Habitat. Parasitic on Sebastes norvegicus ; usually 

 found fixed in the angles formed by the junction of the 

 gill-covers with the gill-arches. On specimens of 

 Sebastes captured in the North Sea and landed at the 

 Fish-Market, Aberdeen, in February 1908 (T. Scott). 



9. Chondracanthus zei De la Roche. 

 (Plate XLI, fig. 5; Plate LVI, fig. 13.) 



1811. Chondracanthus zei De la Roche. (41) p. 270, pi. ii, fig. 2. 

 1822. Chondracanthus delarochiana Blainv. (24) p. 422, pi. xxvi, fig. 

 13. 



1829-1843. Chondracanthus zei Guerin-Meneville. (55) t. 9, fig. 9. 



1831. Chondracanthus zei Burmeister. (26) p. 325. 



1832. Chondracanthus tuberculatus Nordmann. (89) p. 118. 



1850. Chondracanthus zei Baird. (4) p. 327, pi. xxxv, fig. 1. 



1851. Chondracanthus zei P. J. van Beneden. (11) p. 110, pi. iv, figs. 5-7. 

 1892. Chondracanthus zei T. Scott. 10th Ann. Report Fishery Board 



for Scotland, pt. iii, p. 262. 



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



1900. Chondracanthus zeus T. Scott. (112) p. 167, pi. viii, fig. 1. 



1906. Chondracanthus zei Norman & T. Scott. (88) p. 217. 



Female. Body short, moderately stout, and of a 

 somewhat ovate form. Head small, orbicular ; thorax 

 very short, narrowed behind the head where it forms 

 a kind of neck. The genital segment, with which the 

 thorax appears to be more or less coalescent, flattened 

 and becoming gradually and considerably wider pos- 

 teriorly. Abdomen small and rudimentary. A short 

 horn-like process extends outwards from both sides of 

 the thoracic segment and there is a trifid process on 



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