300 Part III. — Tvcntidh Annual liepoH 



on October 10th, 1901, and forwarded to the Laboratory at Bay of Nigg. 

 My sou has also obtained the same species on Raia c'avata captured in 

 Beaumaris Bay.* Professor P. -J. van Beneden in his work on the Fishes 

 of the Coast of Belgium (p. 16) records this Trematcde also from the 

 cloaca of the Grey Skate, Raia hatis . 



Krliyer, after whom this Trematode is named, discovered the species on 

 Raia radiata, taken in the Kattegat,t and it is described very shortly 

 by Diesing in Vol, I. of his Sysfema Ilehnintlmm, published in 1850 

 (p. 431). In 1856 M. C.-T. Hok published a special work on this 

 parasite, Avhile Van Beneden and Hesse in their Recherclies sur les 

 Trematodes (p. 79) refer to a few of the more important characters which 

 serve to distinguish this species from others of the family Tristomatidae 

 to which it seems to btslong. Two of the more obvious of these 

 characters are, (1) the posterior sucker has seven rays and two spines, 

 and (2) the small sucker which in most of the Tristomatidie is present on 

 each side of the mouth at the anterior end is in this species apparently 

 wanting. The authors referred to appear to consider the latter peculiarity 

 as of special interest, for they remark " Ce qu'il ofFre de plus remarquable 

 jusqu'a present, c'est que, tout en appartenant a la famille des tristoinides 

 les ventouses anterieures semblent faire completement defaut." 



This parasite, besides occupjdng a peculiar position on the fish, is usually 

 of an opaque white colour, corresponding very closely with that of the 

 skin on which it is adhering, so that unless the observer knows before- 

 hand what to look for, it is easily missed. If specimens with nearly ripe 

 eggs be closely examined, the sides (indicated in the figure by the darker 

 shading) will be seen to be of a faint yellow colour. The general form, 

 as might be expected, varies considerably, but that which is indicated by 

 the figure seems to be the more normal one. 



Genus Acanilwcofijle, Monticelli, 1888. 

 (Saggio di una morfologia dei Trematodi, p. 97.) 



Aranthoi'otyle monticellii, T. Scott, sp. n, pi. XIII., figs. 31-33. 



A single specimen of a small Trematode was obtained on the gills of 

 a Thoriiback Skate, Raia rlacata, sent from the Fish Market at Aberdeen 

 in April, 1901 — the fish was captured in the North Sea. This 

 Trematode belongs to the genus Aranilwrofijle instituted by Fr. Sav 

 Monticelli in 1888, but does not appear to agree with any of the species 

 already described. There have been three species of Acanthorofyle 

 described by Monticelli, and they have all been found adhering to the 

 skin of specimens of the Thornback Skate {Raia claoata) captured at 

 different times in the Gulf of Naples. The following are their names, 

 arranged in the order in which they were described. 



(1.) AranfhocotyJe loUancoi, Monticelli, described in 1888 in a work 

 entitled Saijgio di una morfologia del Trematodi (p. 13). This species 

 was obtained on the dorsal surface of the Thornback Skate, Raia clarafa, 

 captured in the Gulf of Naples in December, 1887. It does not appear to 

 be a very rare species, but is easily missed ; it measures from three to six 

 millimetres in length, and its colour closely resembles that of the skin to 

 which it is attached. 



* Fifteenth Annual Report of the L.M.B.C., and their Biol. Station at Port Erin (Isle 

 of Man), December, 1901, p. 13. 



tl.V. Beneden and Hesse, in their Rwharches (p. 79),state that Kroyer found the worm 

 which served for the establishment of the genus in the rectum of Raia halis, but Diesing's 

 record is " Habitaculum— iicu'« rcuUahi ; in corporis super ficie, Kattigat—( /uoyer). " 



