240 ORTHAGORISCUS MOLA. 



three of those species have never been found to inhabit any 

 other fish. 



Subjoined is a short description of these Entozoa, speci- 

 mens of which I have the pleasure of presenting to the Na- 

 tural History Society. 



Di STOMA contortum. 



On the gills of the sun-fish were a great number of this 

 species. 



They are cylindrical ; the longest 10 or 11 lines in length ; 

 colour white anteriorly, yellowish-red posteriorly : they almost 

 all assumed a curved form (as Rudolphi has described, and 

 from which he has given the name). 



The anterior pore is small and circular, the ventral larger, 

 elliptical, or circular ; in some seated upon a peduncle nearly 

 the length of the neck. The neck measured nearly 3 lines in 

 largest specimen, it is convex upon dorsal, concave on ventral 

 surface ; it, as well as the head, is armed, particularly upon 

 the convex surface, with numerous minute spines ; these are 

 not continued posteriorly beyond the ventral pore. The body 

 is cylindrical, its greatest diameter being behind the ventral 

 pore, and diminishing gradually towards the caudal extremity. 

 The ova are very small, and exceedingly numerous ; they 

 have a yellow colour, and appear to be the cause of that 

 colour in the posterior part of the body. 



This species has only been found upon the gills of the 

 Orthagorisctis mola. 



Di STOMA nigroflavum. 



The intestines of the sun-fish contained several Distoma 

 which have most of the characters of Distoma nigroflavum^ 

 but I could not see the aculei which Rudolphi describes upon 

 the head and neck. 



The longest specimen was an inch and a half, others about 

 three quarters of an inch ; their colour in some parts black, 

 in others yellowish ; the head white. 



The ventral pore is pedunculated ; the peduncle in a few 

 being as long as the neck, from which circumstance they bear 

 a close resemblance to the Distoma furcatum, and might 

 even pass for this species, as Rudolphi has remarked. The 

 body of the animal is cylindrical and slender, nearly of the 

 same diameter throughout ; the skin is flaccid. 



This species Rudolphi has only found in the alimentary 

 canal of the Orthagoriscvs mola. 



