SOME PABASITIC COPEPODA. 51 



are not very satisfactory. He says the head passes insensibly into the thorax without 

 narrowing to form a neck, so that at the first glance you do not know where the 

 head is. This description certainly does not apply to the parasite from the Piked 

 Dogfish; but after a careful comparison of my specimen with Kurz's figures and 

 description (op. cit.) of Brachiella pastinaca, I think it is correct to identify it as that 

 species. T. Scott obtained two specimens in the nasal fossae of Try goji pastinaca, Linn., 

 but unfortunately they were lost in the post and he was not able to give any figures 

 {pp. cit. p. 278). It would seem to be a somewhat rare species. 



The curious position of this parasite (PL 8. fig. 6) is very remarkable. The head is 

 thrown back, the arms (first rnaxillipeds) stretched out, and the posterior processes 

 turned up almost at right angles to the body. Kurz's description of the general form 

 of the body is accurate, but a short account of the appendages and some more figures 

 may be useful. The cephalic shield which covers the dorsal surface of the head is made 

 up of two plates, down the sides of which run strong chitinous rods of a yellow colour. 

 There is a more slender rod of chitin between the two plates. 



Appendages (female). 



First Antenna (PI. 9. fig. S, A. 1 ). — Slender, four-jointed, the terminal joint bearing 

 three setae of different shapes, and the second joint one small seta. 



Second Antenna. — Biramose, thick, and blunt; outer branch thicker than inner 

 branch, bearing one or two small hooks and covered with fine bristles. 



Mandibles (PI. 8. fig. 7). — These lie inside the mouth-tube and are long and slender ; 

 they differ somewhat from Kurz's description and figure (p. 390, pi. xxvi. fig. 36). He 

 mentions three principal teeth with three smaller teeth alternating with them, the five 

 following teeth, with the exception of the first, being considerably smaller. In the 

 specimen from Acanthias vulgaris there are three large curved teeth. Between the two 

 first of these are two very small teeth (only one is shown in the figure). These five 

 teeth are followed by two straight and sharply pointed teeth, and these again by two 

 more, which are very slender and delicate. There are nine teeth in all. Beyond the 

 teeth the inner margin is produced into a rounded cutting-edge. 



At the sides of the mouth-tube, just anterior to the first maxilla?, are a pair of slender 

 clawed appendages (PI. 9. fig. 8, p.), each composed of a stout basal joint and a slende. 

 curved claw. Thompson *, in his description of Brachiella parkeri, mentions and figures 

 somewhat similar structures ; he calls them " maxillary palps." 



First Maxillce. — See Kurz (op. cit.). 



Second Maxillce (PI. 9. fig. 8, Mx.~).— Kurz does not describe these appendages, 

 but his figure (pi. xxvii. fig. 45) corresponds fairly well with my drawing. They are 

 two-jointed, the basal joint stout and bearing on the inner margin, just below the 

 articulation of the terminal joint, a small pad covered with tiny bristles. About the 

 middle of the inner margin is a small seta, and below this another small pad with 

 bristles. The terminal joint is slender and curved, its edges having strong chitinous 

 supports ; at its end is a curved claw with a small tooth on its inner edge. At the base 



* 1889. ' Transactions of the New Zealand Institute,' vol. xxii. (5th of new series) p. 374, pi. 28. fig. 8 a (p.). 



