437 



Flemming (safranin, gentian violet, orange G) combine with the sa- 

 franin, and not with the violet. 5) The stilet-basis is slightly constricted 

 medially. 6) There are 10 instead of 9 longitudinal nerves in the pro- 

 boscis. 



S. asefisoriatum is larger than S. EilharcU, attaining a length of 

 18 mm, and is of a bright orange color, but apart from these differ- 

 ences, and the six given above, closely resembles the latter species. 

 There are as a rule 3 pairs of eyes, with two eyes in each pair; 

 but I have also noticed 5, 7, or 8 eyes. The rhynchocoel does not 

 quite reach the posterior end of the body, which comparative short- 

 ness is a generic characteristic. The nephridia extend from in front 

 of the brain to the anus, and show the same histological structure 

 as in S. Eilhai'di, though I have not been able to determine whether 

 there are several consecutive pairs of these organs owing to lack of 

 material (my description of the nephridia in S. Eilhardi will appear 

 shortly in Spengel's Zool. Jahrbücher). S. asensoriaium is herm- 

 aphroditic, and in all probability protandric, though as I sectioned only 

 eight individuals, this latter point could not be finally determined. In 

 the gonads of all (with one exception , in which none of these organs 

 were to be found), immature but large ova were present; and in the 

 germ-epithelium of a few gonads in each of the seven inividuals ripe 

 spermatozoa, as well as spermatocytes and spermatogonia were found, 

 leaving no doubt that in a few gonads of each specimen the elements 

 of both sexes were in process of development. Further, the smaller 

 the individual was, the greater was the proportion of gonads showing 

 spermatogenetic stages. But as there were no individuals at hand in 

 which all the gonads contained spermatogenetic elements, for there 

 were no specimens less than 6 mm in length, I can only conclude from 

 my previous observations on S. Eilhardi^ that the Pennsylvania species 

 is likewise protandric , and that the individuals examined had passed 

 through the male stage, had in fact lost nearly all the male elements, 

 and had almost arrived ad the complete female stage. 



The stream in which I collected these worms was less than a yard 

 in breadth, and at no place more than a foot in depth; this fact is 

 mentioned, because most freshwater Nemerteans have been found in 

 larger streams and rivers. 



The only other freshwater forms of this group which have been 

 described from North America, are the following: Nemertes polyhopla 

 Schmarda, from Lake Nicaragua: Emea lacustris Leidy, from the 

 Schuylkill River; and Tetrastemma aquarium dulcium Silliman, from 

 New York State. Of these, Schmarda's form is very aberrant in re- 

 gard to the structure of its proboscis ; while as I have already shown 



