of the Fishery Board for Scotland. 



279 



This Trematode does not agree with any genus or species known to me. 

 Habitat. — In the nasal fossae of Trygon pastinaca, captured in Dornoch 

 Firth, October 1903. 



Heterocotyle padinacai, gen. et sp. nov. PI. xvii., fig. 14. 



Several specimens of the Trematode described under this name were 

 obtained on the same Trygon yadinaca with the form just recorded, but 

 they were found not in the nasal fossae but on the gills along with 

 Eudactylina minida described in the first part of this paper. 



In this Trematode the posterior sucker is slightly oval in outline — the 

 transverse diameter being greater than that which is longitudinal in the 

 proportion of about 13 to 11. The edge of the sucker is indistinctly 

 crenate, and its ventral surface is divided into eight compartments, which 

 extend from the circumference to near the middle, where they are 

 interrupted by a small diamond-shaped space representing the point of 

 attachment of the sucker to the body. The two lowest compartments are 

 of a slightly larger size than the four upper ones, but the compartment on 

 each side is about double the size of the one immediately above. More- 

 over, these side compartments, together with the two lower ones situated 

 between them, are each sub-divided into two portions by a circular line, 

 as shown in the drawing (fig. 14). About the middle of the band which 

 divides each large lateral compartment from the lower one, there is 

 attached a short rod that terminates in a strong hook. 



The body is of a narrow ovate form and is considerably depressed ; the 

 greatest width is equal to nearly three and a half times the length ; 

 the total length of the specimen represented by the drawing is only 

 1*44 mm. (about of an inch). The anterior end is narrowly truncate, 

 and is without any lateral appendages, as in Phyllonella or Placunella, 

 which it otherwise resembles. 



Besides the occurrence of the four different kinds of parasites from 

 the Sting Ray mentioned here, Prof, van Beneden has obtained on 

 specimens of the same species of fish taken on the coasts of Belgium, not 

 only the Brachiella pastinacw — which he found both in the nasal fossae 

 and on the gills — but also Lerneopoda galei and Ergasilina robusta ; the 

 first he obtained in the nasal fossae and the other on the gills. The same 

 writer also records finding five different kinds of Cestoids in the 

 intestines of Trygon* 



PART III. 



Note on a Post-larval Fish Attacked by Podon leuckarti. 



Plate XVII.— Fig. 16. 



It is fairly well known to students of the Entomostraca that these 

 organisms live to some extent on animal as well as on vegetable matter, 

 and also that they do not always confine themselves to decaying sub- 

 stances, but that living specimens, if small enough and in a 

 weak or sickly condition, are not exempted from being attacked by 

 them. When examining a gathering of living Entomostraca in whicn 

 Ostracoda are frequent, we may occasionally observe a number of these 

 minute Crustaceans crowding round some object of general interest, anu, 

 when the reason for the crowding is investigated, find that they are busy 

 feeding on a dead or dying companion. 



*Les Poissons des cotes de Belgique leurs Parasites et leurs Conimenoeaux, pp. 14, 

 15 (1870). 



