HARD WICKE ' S S CIENCE - G O SSIP. 



35 



is the single eye, the depressed lorica, composed of 

 two separate plates, characteristic of the genus 

 Euchlanis, and in addition the jaws of all three are 

 identical in all their parts, varying only in size. This 

 latter character I consider as of the greatest value ; 

 and if we only knew accurately the structure of this 

 important organ in the various species, it would 

 considerably improve the chances of a correct classifi- 

 cation of the Rotifera. On the other hand, the trochal 

 wreath is not very obviously made up of rounded 

 lobes in the above species, and this fact may induce 

 our authorities to create a new genus, for these and 

 others of a similar character. 



The next Rotifer, Fig. 60, is an extremely interesting 

 one, and is more like a typical Euchlanis, as it bears 

 a strong superficial resemblance to the well-known 



young specimen, which I need not here transcribe. 

 In reference to its having two eye-specks when young, 

 I may say that I put this down on the strength of 

 there being two coloured specks clearly visible in the 

 egg ; it does not necessarily follow that they were 

 eyes, and, if they were, it is remarkable that not the 

 slightest trace of them was visible in the adult Rotifer. 

 It is unfortunate that I have hitherto been unable to 

 clear up this point ; however, some authorities con- 

 sider that the eye-speck possesses less value as a basis 

 of classification than Ehrenberg supposed. On the 

 other hand, it is possible that it might have an eye, 

 which, from absence of colour, or from being deep- 

 seated, I failed to detect. Of this Rotifer Dr. Hudson 

 says, "I have little doubt it is an Euchlanis." 

 Subsequently, however, he expressed some little 



Fig. 59*1. — Dorsal view. 'Animal retracted. 



Fig. 59$. — Side view. Animal exserted. 



Fig. 60. — Euchlanis (?). 



E. dilatata. It differs from it, however, in being a 

 smaller and altogether more delicate Rotifer, and in 

 the character of its toes and mastax, the rami of my 

 specimens being slighter than in that species, and 

 they are turned downwards laterally in a beauti- 

 ful curve. I take the following description from 

 my note-book : "Lorica hyaline, depressed, oval, 

 excised in front, rounded posteriorly ; foot long, 

 cylindrical, jointed ; toes as long as foot, not knife- 

 like, but round, and only slightly tapering ; eyes, in 

 adult, none visible ; two eyes when young ; jaws, 

 large, brachionsean ; rotatory organ consisting of 

 rounded lobes ; water-vascular canals, but no vibratile 

 tags ; eggs large, attached to conferva by a brownish 

 protecting cover (not bands), probably chitinous." 

 Then follows an account of the hatching-out of a 



doubt, probably on account of my not detecting the 

 eye, saying, "I know of nothing like it, and hope 

 you may find it again, so as to complete the descrip- 

 tion." For myself I have now little doubt about it ; 

 the lorica, the trochal wreath, the mastax, the two 

 stomach glands, and coiled water-vessels, all point to 

 the genus Euchlanis, and it more resembles E. macrura 

 than any other species whose description I have seen. 

 It is all but useless, however, trying to identify many 

 of the free-swimming forms of the Rotifera, as it is 

 impossible in some cases to make them agree in all 

 points with any species described in our text-book. 

 In reference to this genus Dr. Hudson, in one of his 

 letters to me, very truly observes : " The species of 

 this genus are in wild confusion, and have, I believe, 

 been described under various names." It is wel) 



