120 THE ROTIFERA. 



the mouth. The family contains the genera Asplanchna and Sacculus, which, while 

 separated from all other Kotifera by the absence of intestine and cloaca, differ also from 

 each other in several important points. The incudate trophi of Asplanchna are massive 

 forceps quite free from an inclosing mastax, and capable in consequence of even plung- 

 ing down into the oasophagus ; but the forcipate trophi of Sacculus are feeble hooks and 

 blades, inclosed in a grape-shaped mastax, and admitting of only a slight protrusion 

 from the mouth. The stomachs also of the two genera are widely different : that of 

 Asplanchna, a spheroidal bag of moderate dimensions ; that of Sacculus, a large sac with 

 six great Cc^ecal appendages nearly filling up the whole of the body-cavity : and, further, 

 Sacculus carries its eggs attached by a thread to a hollow of the posterior surface, 

 while Asplanchna produces its young alive. 



Genus ASPLANCHNA, Gosse. 



GEN. CH. Corona with two apices; trophi incudate, not inclosed within a mastax; 

 stomach of moderate size, spheroidal. Viviparous. 



The various species of this genus differ from each other mainly in the presence or 

 absence of the foot, in the shape of the trophi, in the number and colour of the eyes, in 

 the size and arrangement of the vascular system, and in the external shape and appendages 

 of the male. 



It was in this genus that the first male Eotiferon was discovered ; and, indeed, the 

 great size and transparency of the female, and its habit of producing its young alive, 

 give unusual facilities for the study of the males. Many of the Rotifera deposit their 

 eggs here and there on the stems and leaves of algfe &c., so that it is impossible to 

 identify the males when hatched ; but in the genus Asplanchna the male may be readily 

 seen alive in its mother's ovary. It is a creature of the greatest delicacy, like a bubble 

 of the clearest glass ; and yet the various species can be easily distinguished by the 

 differences of figure. In one the male is a mere reproduction of its parent on a reduced 

 scale ; in another it bears two sleeve-like processes on its sides ; in a third, four such 

 processes ; while one has its ventral surface prolonged into a sheath for the penis. 



A. EBBESBOENII, Hudson. 



(PI. XL fig. 3.) 

 Asplanchna Ebbesburnii . . Hudson, J. Hoy. Micr. Soc. 2 Scr. vol. iii. 1883, p. G21, pis. ix. x. 



Female with one dorsal, one ventral, and two lateral humps; eye single; rami with 

 singly pointed ends, not serrated ; contractile vesicle expanding to more than half the 

 lody-cavity ; vibratile tags often forty on each side, and arranged in straight lines ; 

 ovary horseshoe-shaped ; male with two additional, lateral, humps, below the neck. 



This fine and rare Rotiferon was discovered by Mrs. Tupper Carey in 1880, in a 

 duck-pond in the vicarage of Ebbesborne Wake ; and, strange to say, this, at present, is 

 its only known habitat. It differs from all other species of the genus in its outline, 

 which is not bell-shaped, and in its possession of four sleeve-like prolongations of the 

 cuticle ; one on the dorsal surface, one at the hind end of the ventral, and one on each 

 side of the body below the head. All these appendages are empty of organs, and some- 

 what flaccid when the animal is swimming quietly ; but, when it draws in its head, they 

 are driven out stiffly from the general surface. Fine muscular threads tie their ex- 

 tremities to various parts of the body, and serve to shorten the processes when the head 

 is again protruded : the two side appendages have their tips connected by a fibre passing 

 straight through the body from the one to the other. The head is conical with two 

 apices ; and in the hollow between them, a little towards the ventral surface, lies the 

 buccal orifice, with two small style-bearing prominences on either side of it. The 

 ciliary wreath is a simple ring of cilia surrounding the coronal cone, and Lent down 



