1907.] NATURAL SCIENCES OF PHILADELPHIA. 85 



The small size of the cells of this species of Dinophilus, and the gen- 

 eral lack of distinctness in the boundaries of tissues and organs, made 

 imperative the use of the highest powers. In studying and drawing 

 sections a one-twelfth Zeiss oil immersion was employed almost ex- 

 clusively. This necessitated a brilliant illumination. After the loss 

 of much time from cloudy and dark weather, I had recourse to artificial 

 illumination, as recommended by Child (1900). For this purpose I 

 used a burner of the Welsbach type, mounted about nine inches above 

 the table. Two blue glasses were placed in the cell below the con- 

 denser, one dense and one thin. I heartily concur with Child in the 

 opinion that this means of illumination is sviperior to daylight, at 

 least when high powers are employed. The light, when filtered 

 through the blue glasses, is almost perfectly white, does not tire the 

 eyes, is of constant and unvarying intensity, and, above all, is always 

 available. 



In making the reconstructions which constitute Plate XII, fig. 1 and 

 text fig. n^, a modification of the method given by Lee {Microtomist's 

 Vade-Mecum, 5th ed., 1900) and ascribed to Woodworth, was employed. 

 The camera lucida was, however, used in place of a micrometer. Such 

 reconstructions proved of the greatest value in determining the rela- 

 tions and connections of parts which run through a number of sections, 



III. Anatomy. 

 1. External Fonn and Specific Characters of Dinophilus conklini. 



The Dinophilus which forms the subject of this paper has been 

 found, after comparison with the descriptions of the other members of 

 this genus, sufficiently different from them to warrant description as a 

 new species. I take great pleasure in bestowing upon it the specific 

 name conklini, in honor of Prof. E. G. Conklin, of the University of 

 Pennsylvania, who was the first to find this form. This species has 

 so far been found only in the aquaria belonging to the University of 

 Pennsylvania. Prof. Conklin, however, informs me that he is of the 

 opinion that it is brought in on the Ulva obtained by dredging at Sea 

 Isle City, New Jersey. A comparison with other species and the 

 enumeration of specific characters are postponed to the end of this 

 section. 



The females of Dinophilus conklini are very wormlike in their form 

 and general aspect. Text fig. I, although drawn from a fixed and 

 stained preparation, shows little or no distortion, and represents the 

 animal in a state of moderate extension, such as it often naturally 



