528 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.51. 



over that of Ehrenberg, but his achievement was partly nulHfied 

 by Hudson in the Supplement, where all the Ehrenbergian names 

 are rehabilitated. 



In dealing with the Rotatoria grouped under the name Metopidia 

 by Hudson and Gosse it is necessary to separate them into two genera, 

 Leimdella and Lophocharis, as proposed by Iroso in a recent paper. 

 This division was suggested by Ehrenberg in 1838/ but for conveni- 

 ence he left the only then Imown species of Lophocharis in the genus 

 Lepadella. The anatomy of the two genera differs in so many 

 important points that no serious objection can be urged against their 

 separation. Lepadella is without doubt descended from forms that 

 until comparatively recent times did not have the integument 

 stiffened into a lorica except on the dorsal surface. If additional 

 evidence were needed on this point, it is furnished by the closely 

 related genus Colurella i=Colurus), which even today is without a 

 ventral plate; it is true that the edges of the dorsal plate have in 

 this case curved toward each other, so as to leave only a narrow 

 ventral slit unprotected by the lorica, thus accomplishing the same 

 object in a different way, but the history of the development of the 

 lorica is obvious. Lophocharis, on the contrary, has a box-like 

 lorica, which shows no evidence of having passed through the 

 Colurella^stsige, and it is highly probable that the lorica was developed 

 gradually and simultaneously over the entire surface of the body. 

 The peculiar structure of the posterior end of the body in the 

 Lepadellids, with the foot projectmg through the ventral plate at 

 the anterior end of a "foot groove, " occupying about one-third of the 

 length of the ventral plate, is totally absent in Lophocharis, and so 

 is the protective dorsal hood over the corona. The Lepadellids 

 have two frontal eyespots, while Lophocharis has, according to 

 Iroso, a single eyespot on the ganglion. 



While both genera belong to the group centering about the genus 

 Euchlanis, they must be assigned to different branches of it. Lepa- 

 della (with Colurella) appears to be more nearly related to the genus 

 Euchlanis than to any other, while Lophocharis belongs to a small 

 group typified by the genus Trichotria {=- Dinocharis) . This group 

 also includes Macrochaetus { = Polychaetus) and TfoZgra Skorikov, the 

 last-named genus with the single species F. spinifera { = DistyU 

 spinifera Western), which is in no way related to the genus Le- 

 cane (including the genera Cathy pna Gosse and Distyla Eckstein, not 

 of Eichwald), as it is without any of the generic characters of typical 

 Lecanids. 



As a rule no locahties have been given for the species considered 

 in this paper. Two reasons may be advanced for this omission. 

 The more easily recognized species, which may with a fair degree 



I Infusionsthierchen, p. 438. 



