JUl 20 1896 
JOURNAL 
OF THE 
ROYAL MICROSCOPICAL SOCIETY. 
JUNE 1896. 
TRANSACTIONS OF THE SOCIETY. 
Y. — Notes on the Genus Apsilus and other American Botifera. 
By Dr. Alfred C. Stokes. 
{Read 18 th March , 1896.) 
Plate VI. 
In Hudson and Gosse’s learned monograph on the Rotifera the genus 
Apsilus is made to include but two species, Apsilus lentiformis 
Metsch. (of which the two American forms A. vorax Leidy and 
Cupelopagus bueinedax Forbes are made the synonyms), and A . hiper a 
Foulke, which Dr. Leidy claimed to he synonymous with A. lenti- 
formis. While the internal structure of all these forms may be, and 
I think will prove to be, closely similar, they seem to possess sufficient 
outward variation from one another to be separated as four distinct 
species. If internal structure, to the exclusion of external form, were 
to he considered as entitling any Rotiferon to specific rank, there 
would be a sudden reduction in the number of species now recognised. 
A glance, however, at Hudson and Gosse’s monograph of any single 
genus will afford ample proof of the value placed by the authors upon 
external form. Miss S. G. Foulke, in her paper £ On a New Species 
EXPLANATION OF PLATE VI. 
Fig. 1. — Apsilus bueinedax Forbes, dorsal view, g, ganglion ; i, intestine ; ov, ovary ; 
p , proventriculus ; st, stomach. 
,, 2. — A. bueinedax , ventral view, c, cloaca; cv , contractile vesicle; oe, oeso- 
phageal ring ; i, intestine ; m, intestinal (?) gland ; ov, ovary. 
,, 3. — A. bueinedax , side view of coronal cup; slightly altered from Miss Foulke 
after Forbes. 
„ 4. — A. bipera Foulke, dorsal view of coronal cup ; slightly altered after Miss 
Foulke. 
„ 5. — Trophi of A. lentiformis Metschnikoff. From Hudson and Gosse after 
Metsch nikoff. 
„ 6. — Trophi of A. bueinedax. 
„ 7. — Colurus agilis, lateral view. 
,, 8. — C. agilis, ventral outline of lorica. 
„ 9. — 0. agilis, diagram of the curve of the frontal hook. 
10. — Copeus guinquelobatus sp. n , dorsal aspect. 
„ 11. — Contour of the protruded auricle of C. guinquelobatus. 
1896 
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