46 bulletin: museum of comparative zoology. 



5. Glossiphonia elegans Vekrill (1872). 



Plate 7 ; Plate 3, Fig. 5 ; Plate 3, Pig. 11. 



Clepsine elegans Verrill f'72) ; (1) C. pallida Verrill ('72) ; C. patelliformis 

 Nicholson ('73). 



a. Habitat, Size, Color. 



This species is very closely related to the European G. complanata L. and G. 

 concolor Apathy. Blanchard ('94), indeed, considers it identical with G. com- 

 planata L. and regards G. concolor Apdthy as merely a variety of the same 

 species. However, both Apathy ('88) and Oka ('94) testify to the perfect dis- 

 tinctness of G. coniplanata and G. concolor, which occur together in Europe. 

 I have myself compared animals of the species to be described with alcoholic 

 specimens of G. complanata from Ziirich, Switzerland, and find certain small 

 but constant differences between the two. I shall therefore describe the animals 

 which I find here in the vicinity of Cambridge under the name proposed by 

 Verrill in 1872, recognizing, however, that they are very closely related to the 

 two European species (or varieties) named. 



G. elegans (Plate 7) is found in localities similar to those frequented by G. 

 stagnalis, often in company with that species. It is considerably larger, being 

 much broader and thicker in proportion to its length, though scarcely longer. 



In its movements it is more sluggish, resembling closely the small G. het- 

 eroclita in that regard. It adheres to the side of the aquarium with a tenacity 

 displayed by no other of our species except G. parasitica. 



The form of the body at rest is elliptical. 



The largest individuals which I have collected measure, when alive, as 

 follows : — 



Length, fully extended, 28 mm. ; at rest, 14-18 mm. 



TFidth, fully extended, 5 mm. ; at rest, about 7 mm. 



Color. — Small individuals are usually of a bright, transparent green color. 

 Adult animals, viewed with the naked eye or through a hand lens, appear of 

 a reddish or greenish brown color, and are darker above than below. 



The head is colorless. The dorsal surface of the body is marked with 

 numerous small circular white spots, about the width of a body-riug in 

 diameter. These spots are so placed as to form transverse and longitudinal 

 rows, just as do the similar spots of G. fusca. The transverse rows fall on the 

 sensory (middle) rings of their respective somites, each row containing seven 

 spots, when the full number is present. Each of these seven spots falls in a 

 different longitudinal row, there being three pairs of rows arranged sym- 

 metrically with reference to an unpaired (median) row, exactly as in G. 

 fusca. The paired rows may be designated respectively paramedian, inter- 

 mediate, and marginal, for they occupy practically the same position on the 

 body as do the rows of white .spots in the ca.se of G. fusca, and the rows of 

 papilUo in that of G. parasitica (Figure 6). 



