1905.] NATURAL SCIENCES OF PHILADELPHIA. 6G9 



Traohelomonas verrucosa Stokes. PI. XLI, fig. 2. 



Trachelomonas verrucosa Stokes. 1887. Proc. Amer. Philos. Soc, XXI"\'. 



"Lorica subspherical, colorless, the entire surface covered with 

 minute hemispherical elevations, the anterior extremity slightly 

 emarginate." 



This species is not uncommon in the Delaware Valley, and it is 

 especially plentiful at times in tidal ditches. As observed, it agrees 

 closely with the description as quoted from Dr. Stokes, except only 

 that the lorica is very generally brown instead of colorless. The hemi- 

 spherical elevations sometimes show a slight tendency to elongate. 

 Observed maximum diameter 24 /i. 

 Traohelomonas rugulosa Stein. PI. XLI, figs. 7 and 8. 



Trachelomonas rvgulosa Stein. 1878. Infusionsthiere, III. 



Lorica subspherical, thick-walled, brown. Surface with short, 

 irregular, transverse to oblique, crooked wrinkles. Aperture plane, 

 generally surrounded by a flat, smooth area. 



Observed maximum diameter 23 /j.. 



It is a present tendency to reduce this form to a variety of T. volvo- 

 cina. Immature individuals of the spheroidal species show resem- 

 blances that are more or less puzzling. No doubt these species are 

 closely related and of recent differentiation. But the well-developed, 

 highly colored, mature loricse seem to differ with a sufficient constancy. 



Published figures of the present species, mostly copied from Stein, 

 are naturally quite as nebulous and unsatisfactory as Stein's own. 

 Since it is proposed to insist herein upon the apparent validity of this 

 species, the mature lorica, as it occurs along the Delaware, is illustrated 

 in PL XLI, figs. 7 and 8, with such fidelity as was attainable. The 

 markings vary in development from faint, elongated dots to crooked, 

 confluent ridges. These ridges are by no means uniformly arranged 

 spirally in the manner indicated in Stein's figm-es; and the internal 

 spiral vestiges, shown in one of these figures, can scarcely constitute 

 a specific character, since the like may often be seen, under favorable 

 conditions, in almost any species of the genus. 



The form figured was collected in numbers in Tinicum, August, 1903. 

 Others quite similar were observed at Penn Valley, September, r904. 

 The same species, collected at Hammonton, New Jersey, in 1902, 

 showed confluent rugosities that could only be described as cerebroid 

 convolutions. In none of these was observable any tendency toward 

 production of the aperture into a tube like that of T. volvocina. In 

 every way T. rugulosa seems much more closely related to T. verrucosa 

 than to T. volvocina. Certain plainly immature conditions resemble 



