491 



of the suckers, intestine, and genital glands. The pigment however 

 is not dispersed but in the form of two black eye-spots. 



46) Acrodactyla petalosa Ldinàei. 



Intes. Acipe7iser rubicundas Le S. (Lake Sturgeon). 



New genus: aycQOç, end; ôcc-atuIoç, ùnger. 1,92X0,54. In extended 

 specimens the body is uniformly broad, but it is frequently slightly 

 constricted behind the mouth-sucker, broadening from this to the 

 region of the ventral sucker and then tapering to a blunt end. Ven- 

 tral sucker noticeably smaller than oral, at the centre of the body, 

 but, due to unequal contraction of the body, sometimes a little nearer 

 the anterior and sometimes a little nearer the posterior end. Oral 

 0,325, ventral 0.275. 



Ovary close behind and to one side from the ventral sucker. Testes 

 close together, half way between ventral sucker and posterior end, 

 spherical in younger and more irregular in older animals, in a 

 straight line or slightly oblique. Genital opening half way between 

 ventral and oral suckers. Penis large with broad lumen at the an- 

 terior end and extending to near or even beyond the posterior edge 

 of the ventral sucker. Vitellaria from pharynx to posterior end. 



This is the D. 'auriculatum Wedl! of Xinton and it is upon the 

 authority of Looss that I use the above specific designation. 



The three genera Bunodera^ Crepidostomum and Acrodactyla are 

 closely related as shown by the disposition of their genital organs 

 and the presence of "mouth-papillae". With regard to the latter I 

 am of opinion that there is no difference of internal structure in the 

 different species, and that these bodies are too changeable to be of 

 much use in classification. The one difi'erence that appears constant 

 is that in Acrodactyla the ventral papillae are much larger than the 

 other four and, originating close together under the anterior and of 

 the mouth-sucker, they curve backwards and outwards, moustache- 

 like, across the corners of the mouth until their outer, bluntly 

 pointed ends project laterally past the sides of the sucker and 

 posterior to the level of the other papillae. This character together 

 with the position of the genital opening and large size of the penis- 

 sack will distinguish this genus from the other two, while the small 

 tubular uterus containing few eggs distinguish alike Crepidostomum 

 and Acrodactyla from Bunodera. The probability that there will 

 be found a number of species to represent each of these genera ren- 

 ders it advisable to recommend three genera rather than one, for 

 there are as good reasons for separating Acrodactyla as Crepidosto- 

 mum from Bunodera. 



