82 PROCEEDINGS OF THE ACADEMY OF [Feb.; 



THE MORPHOLOGY OF DINOPHILUS CONKLINI n. sp. 



by james a. xelsox, ph.d. 

 Contents. 



I. Introduction. 



The systematic position of Dinophilus has been a subject of con- 

 siderable interest to naturalists ever since the establishment of the 

 genus by Oscar Schmidt in 1848, and the opinions held on this point 

 have been — relatively speaking — many and various. In a former 

 paper on the early development of this form (1904a) I gave a brief 

 review of these; to repeat it here seems superfluous. In the paper just 

 mentioned certain conclusions as to the relationships of Dinophilus 

 were stated, based on a study of its development. In the studies of 

 which the present paper is the result, an attempt has been made to 

 test these conclusions by a study at first hand of the morphology of 

 the same species. This seemed the more desirable, since in the last 

 fifteen years there have appeared but three papers on the structure of 

 members of this group, and those dealt with species different in many 

 respects from the one studied by me. Moreover, the apparent rarity 

 of Dinophilus and its sporadic occurrence was an additional incentive 

 to making the best of the opportunity which presented itself in finding 

 abundant material for the study of its morphology, as well as its 

 development, in the aquaria of the University of Pennsylvania. 



It gives me pleasure to take this opportunity to express my indebted- 

 ness to Prof. E. G. Conklin, of the University of Pennsylvania, for the 

 privilege of taking Dinophilus material from the acjuaria of the Univer- 

 sity ; to the Carnegie Institution for the use of one of its rooms at Woods 



