of the Fishery Board for Scotland. 



163 



Fam. Chondracantiiid^e. 



Genus Oralien, Basset-Smith (Proc. Zool. Soc. Lond., 



April 1899, p. 489). 

 Syn. Lernentoma (pars.), Baird, Brit. Entom., p. 329. 



This genus has been established by Dr. Basset-Smith for Lernaia 

 asellina, Linn. (Lernentoma asellina, Baird), because of the marked differ- 

 ence in the arrangement of the cephalic appendages. In the typical 

 Ghondr acanthus these appendages are arranged in more or less proximity, 

 but in Lernaa asellina the head, which is rounded anteriorly and 

 provided with antennules and antenna as well as lateral lobe-like projec- 

 tions, is produced behind into a cylindrical and moderately elongated 

 neck, at the base of which, where the neck joins tj thorax, is situated 

 the mouth and the several mouth organs. By this arrangement a 

 considerable distance intervenes between the antennal appendages and the 

 mouth parts. But besides this departure from the arrangement of the 

 parts usually observed in the genus Ghondr 'acanthus , the general appear- 

 ance of the animal also exhibits a marked difference from that of the 

 other species belonging to that genus. 



Oralien asellinus (Linn.). (PI. VII., figs. 16-18.) 



1761. Lernoea asellina, Linn., Fauna Suec, 2 lOl. 



1838. Chondr acanthus triglce, Kr. Naturh. Tidsskrift, k. i., 



vol. ii., p. 135, PI. III., fig. 3. 

 1850. Lernentoma asellina, Baird, op. cit., p. 329, PI. XXXV., 



fig. 4. 



In this species the front part of the head is enlarged by the develop- 

 ment of a lobe-like projection on each side ; this part is usually buried 

 deeply in the tissues of the fish. The antennules are short, moderately 

 stout, simple appendages. The mandibles, which are somewhat similar to 

 those of Chondr acanthus, are stout and falcate, and their convex margins 

 are fringed with short but moderately stout spines (fig. 18). The maxillae, 

 maxillipedes, and other appendages are somewhat similar to those of 

 Chondracanthus cornutus. 



The size of specimens varies to some extent; the more usual dimensions, 

 however, seem to be as follows : — Length, exclusive of ovisacs, about 

 8 mm. ; length from front of head to end of ovisacs?, about 12 mm. A 

 specimen from a common gurnard, Trigla gurnardus, measured only 

 5 '5 mm. in length of body and 8*5mm. to the extremity of the ovisacs. 



I have obtained the species on the gills of gurnards, plaice, halibut, and 

 other fishes captured on all parts of the Scottish coasts examined by us. 



It is of interest to note- that in the various works on the copepod 

 parasites of fishes which I have consulted no two authors agree in their 

 figures of this species. It may be that there is more than one species 

 included in Ghrondracanthus asellinus, or the differences referred to may 

 be due to the variableness of the species. 



Genus Ghondr acanthus, De la Roche (1811). 

 Syn. Lernentoma and Ghondr acanthus, Baird. 



In this genus the head, though distinct, is not separated to any great 

 extent from the thorax. The antennules are usually more or less 

 conspicuous in front of the head, and these and the antennae are in close 

 proximity to the mouth organs. The genital segment is more or less 

 cylindrical, as in Ghondr acanthus cornutus, or constricted, as in 



