DOUBTFUL AND REJECTED GENEEA. 59 



stomach. This latter bears no gastric glands, and ends in a very short intestine with 

 a cloacal openmg on the ventral surface, just before the tail. The eye is a refracting 

 lens, resting on a top-shaped mass of purple-red pigment ; and the whole is enclosed in 

 an egg-shaped transparent capsule. ' 



The only other organ is what appears to be a large, cylindrical, two-lobed ovary, 

 lying on either side of the stomach. If the animal be a Rotiferon, it is very badly 

 described. Herr Corda found it, in WM, at the weirs between the islands of the 

 Moldau, below Prague. 



Length, ^4^ inch. 



Genus DIPLOTROCHA, Schmarda (134). 



Formed by Herr Schmarda to receive a free-swimming Rotiferon, I). pUjcjura, found 

 at Cairo. Its pear-shaped body is surmounted by a short cylindrical head, and tapers, 

 continuously with a wrinkled foot, to two short toes. The corona, according to Schmarda, 

 consists of two complete parallel circles of cilia surrounding the upper and lower 

 margins of the cylindrical head. There is a pair of long narrow teeth curved towards 

 each other; a short circular stomach; and a red, semilunar, cervical eye. No other 

 details are given, and no mention is made of the position of the mouth, so that it is 

 impossible to say what this creature really was. As it was only about ^-L^ inch in length, 

 it might have been some young Rhizotan. Schmarda's figure is of little value. 



( Genus DIURELLA, Eyferth (46). 

 I Genus HETEROGNATHUS, Schmarda (135). 

 Each of these includes several genera of the family Battidida. Of the latter, four 

 species, viz. brachydactylus, dujlenus, macrodactylus , notommata, said to be new, are 

 given by Schmarda ; but see note 1, Sup', p. 8. Of the former, tigris and rattulus have 

 been mentioned vol. ii. pp. 05, G7 ; while stylata (46), and insignis (Herrick, 175), I 

 cannot determine. 



Genus HYDRIAS, Ehrenhenj (42). 



This genus contains one species, cornigera, a Philoduie without eyes, proboscis, or 

 spurs ; and with its corona divided into two separate circles of cilia, each jjlaced on a 

 separate projection of the body. This kind of corona lias been attributed, by numerous 

 observers, to various Eotifera that do not possess it : in fact, no such corona is known. 

 Ehrenberg found this Rotiferon in standing water in Africa ; but it is too imperfectly 

 observed to be admitted. 



Genus MACROTRACHELA, Milne (18G). 



Mr. Milne proposes this genus for three-toed Philodinadce, having the pre-intestinal 

 part of the body decidedly longer than the post-anal. All the species are CalUdince and 

 have already been described (see Index), exceijt musculosa and tridens, which are 

 doubtful species. 



Genus MONOLABIS, Ehrenberg (42). 



This genus of Ehrenberg is intended to contain such Philodinadce as have no pro- 

 boscis, but have two frontal eyes, and a spurless foot with two small toes. There are two 

 species, conica and gracilis ; the former has the shape of a stout flattened cone, taper- 

 ing to a foot continuous with the body, and bearing two minute toes ; the latter is of 

 similar shape, but much more narrow and slender. Conica has three transverse teeth 

 in each ramus, and a ventral antenna : gracilis has two transverse teeth in each ramus, 

 but no antenna at all. 



It is obvious that whatever these Eotifera may have been, they were not Philo- 

 dinadce. The absence of the proboscis, of the characteristic sliding joints in the foot 

 and body, and of the spurs on the foot, sufficiently show this. Possibly they were 

 yoimg Rhizotans ; but the ascription, to one of them, of a single ventral antenna, makes 

 it more than probable that the animals were imperfectly observed. 



