88 BULLETIN : MUSEL"^ OF COMPARATIVE ZOOLOGY. 



gated by Salensky ('72), is oue of the Loricata. Only Eospbora, upon 

 which the work of Tessiu ('86) was done, belongs, together with 

 Asplanchua, to the swimming lUoricata. But even these two are widely 

 separated, Eospbora possessing a foot and anus, like the majority of the 

 Rotifera, whereas Asplanchua possesses neither. 



The only work which has been done upon the early development of 

 any species of Asplanchua is that by Leydig ('54) and Lameere ('90). 

 The latter observed in the living egg of Asplaucha Sieboldii the formation 

 of the polar cell and the first and second cleavages, but did not carry his 

 work further. Leydig ('54) observed the cleavage of the egg, and 

 figured the four-cell stage in the same species, but does not give any 

 detailed description. I know of no other work dealing with the early 

 develoj)meut of any species of Asplauchna. 



I have examined the early stages of both Asplanchna Herrickii de 

 Gueme and Asplauchna priodonta Gosse, of which the material collected 

 in the Gi'eat Lakes contained about equal numbers. Asplanchua Herrickii 

 was chosen for special investigation on account of the greater size of the 

 embryos and adults. The development of Asplanchua priodonta was 

 examined for comparison, and notes upon the embryology of this species 

 have been given in couuectiou with the fuller discussion of Asplauchna 

 Herrickii. 



1. Previous Knowledge of Asplanclana Herrickii. 



It will be well to give here a brief review of previous i-eferences in the 

 literature to the little known species Asplanchna Herrickii. It was 

 first figured by Herrick ('84, Plate V.), and described in the explanation 

 of plates as "flask-shaped Rotifer, hermaphrodite, with eggs and sperm,'' 

 but no further description was given and no name was proposed. 

 Herrick in a second paper ('85, p. Gl) again mentious this form, but 

 adds nothing to the description. 



In 1888, Jules de Gueme ('88) reproduced Herrick's figure of the 

 jaws, and on the basis of this held that the species was new, and pro- 

 posed for it the name Asplanchna Herrickii. 



Hudson and Gosse ('89) included Asplanchua Herrickii in their list 

 of " doubtful species." 



Daday ('92) admits Asplauchna Herrickii as a valid species. 



Up to this time no observer since Herrick had reported finding th.s 

 species. But in this same year, 1892, "Wierzejski ('92) gave an account 

 of its presence in Galicia, with a description, and figures of the jaws 

 and the peculiar glandular organ which Herrick had mistaken for 



