Rolifera of the Family Asplanchnidse. 35 



water. Although it is one of the largest known Rotifera, its 

 extreme transparency has concealed it from observation. It 

 would remain invisible if its viscera were not generally filled 

 with yellowish matter. Yet it is very difficult to distinguish 

 in a somewhat strong light *. 



Schrank gave four figures of this animal, and from these 

 it appears that he had grasped the general features of its 

 organization. Nevertheless many details are wanting, and 

 the mastax, among other things, was not observed ; but there 

 is no doubt as to the identity of the species, as Ehrenberg 

 has already recognized, although, as I have stated, he changed 

 the name f. 



It is to be remarked that Asplanchnopus multiceps is tlie 

 only type of the family which possesses maxillaj terminating 

 in a simple acute point |. 



Gosse seems to think § that this Rotifer is destitute of a 

 contractile vesicle ; but this is very improbable, considering 

 the contrary and concordant observations of Ehrenberg, Ley- 

 dig, and Plate. 



I think that we must identify with A. muUtGeps the species 

 recently described by Herrick under the name of Asplanckna 

 magnificuSj and previously figured by him with no otlier 

 indication than this : — " Deadly enemy to Ckydorus." 

 Truth, however, compels me to add that the figures of the 

 American author surpass in mediocrity anything that it is 

 possible to imagine. The little engravings given by Schrank 

 in 1793 are indisputably better than these quite recent 

 figures. 



Asplanchnopus multiceps , which was discovered by Schrank 

 at Ingolstadt in Bavaria, was found at Berlin by Ehrenberg, 

 in the neighbourhood of Wurzburg by Ley dig, and more 

 recently at Bonn and at Bremen by Plate. Lastly, it has 



* Schrank, ' Naturforsclier/ xxvii. pp. 30-32. It is certain that the 

 transparency of the Rotifera of the family Asplanchnidaa renders their cap- 

 ture very difficult in the vessels in which they are kept aUve. I have 

 had to seek in vain for a long time for one of these animals in water which 

 I knew to be full of it. No doubt this circumstance, coupled with the 

 minuteness of their size, has hitherto prevented the discovery of the males 

 of several species. 



t In 1838. Ehrenberg does not appear to have been acquainted with 

 Schrauk's work when he first described Notommata myrmeleo. 



X From the description (" rami with singly pointed ends ") and fig. 32 

 in the text of Gosse and Hudson (loc. cit. vol. i. pp. 29 and 120) it might 

 be thought that this is also the case iu Asplanchna Ebheshoniei ; but 

 hg. 3 e iu pi. xi. bears an indication of a small tooth, much more marked 

 still in tig. 15 of pi. x. of the previous memoir by Hudson (Journ. Hoy. 

 Micr. Soc. ser. 2, vol. iii., 1883). 



5 Hudson and Gosse, loc. cit. vol. ii. p. 134. 



3* 



