364 PROCEEDINGS OF THE ACADEMY OF [-Mav, 



the creeping and attached forms? Here again we are met with the 

 fact that a knowledge of distribution, and its factors, constitutes a very 

 important ally in the study of phylogeny. 



The present paper is offered as a contribution to the morphology of 

 the Flosculariidse alone. The only thorough account so far of the 

 anatomy of any species of this family is that of Gast on Apsilus lenti- 

 formis. The occurrence of Apsilits, Stephanoceros and four species of 

 Floscularia during the past winter and spring in a pond in the garden 

 attached to our zoological laboratory, enal^led me to study all these 

 forms at the same time, and so to make the desired comparison of them. 

 But until I have had opportunity to examine for myself other families 

 of the group, it would l)e premature to express any opinions upon the 

 phyletic value of the Rotatoria as a whole. 



In regard to the methods of stud\^ the examination of the living 

 animals under slight pressure of the cover-glass has proved the most 

 important. Fixation with hot corrosive sublimate or with Flemming's 

 fluid, and staining with hsematoxylin or carmines were of value in 

 rendering nuclei more distinct, but even in life all the nuclei of the body 

 tissues can be seen. The preparations may be mounted in l^alsam 

 with no shrinkage by passing the objects from the absolute alcohol 

 through graduated mixtures of cedar oil vdth alcohol. Sections were 

 made of Apsilus alone. The complete literature has been cited for 

 Apsilus and Stephanoceros, but for Floscularia only such contributions 

 as concern the internal anatomy. 



APSILUS, Meczn. 



Historical. 



Leidy (1857) described very briefly Dictyophora nov. gen. vorax nov. 

 sp., from the vicinity of Philadelphia. Mecznikow (1866) described 

 Apsilus nov. gen. lentiformis nov. sp., from Giessen; he noted the com- 

 plete absence of ciliary wTeaths, form of the corona, the lateral antennae, 

 intestinal tract, musculature, nephridia, and mistook for the brain a 

 large muscle; he described the male also. Then Leidy (1882) figured 

 his species, and mentioned that it differs from the species of Mecznikow 

 in the lack of lateral antennae and of a ganglion. Forbes (1882) gave 

 a crude figure of and briefly described Cupelopagis nov. gen. bucinedax 

 nov. spec, from Illinois, describing the alimentary tract and the exter- 

 nal form. Foulke (1884) described as a new species Apsilus bipera, 

 from Philadelphia ; the corona was described as a membranous hood or 

 net, two stomachs (the proventriculus erroneousl}' regarded as a 

 stomach), lateral antennae, musculature; she pointed out that the 



