418 DESCRIPTION OF [Rotatoria. 



has a rough (scabrous) lorica, with twelve long and nearly 

 equal spines anteriorly, and four posterior ones ; the two 

 middle ones unequal, and shorter than those of the pre- 

 ceding species. Length, without spines, 1-1 20th. 



Genus CLXXXVIII. Pterodina. The winged Rota- 

 toria include Brachionaea which have two frontal eyes and 

 a simple styllform foot. All the species have a smooth, 

 flat, and soft lorica, like a tortoise-shell {testula); they 

 are curved at the margin. A double rotatory apparatus, 

 and a simple conical foot, having a suction disc at the end, 

 and sometimes cilii, are common to all. P. elliptica alone 

 has a hairy frontal process between the wheels. Transverse 

 or longitudinal muscles exist in all the species. The four- 

 muscled oesophagal head has jaws, with teeth in rows in 

 two species (locogomphia), and double-toothed {zygogom- 

 phia) in P. elliptica; the alimentary canal is constricted 

 [gasterodela], and possesses, anteriorly, two glands; an 

 ovarium is also seen in all the species. Sexual glands and 

 a contractile vesicle are present in P. patina. No evidences 

 of a vascular system have been discovered, and two red 

 frontal points (probably eyes) are the only indications of 

 a system of sensation. 



730. Pterodina patina {Brachioriiis patina, M.) T/ie 

 dish-like Pterodina has a membranaceous lorica, orbicular 

 and crystalline, slightly scabrous near the broad margin, and 

 excised anteriorly between the wheels. This species is very 

 delicate and transparent. Fig. 502 represents a side view 

 of this animalcule, and figures 503 and 504 under views ; 

 the latter having the wheels extended, the former having 

 them withdraAvn, and the anterior margin bent in, so 

 that the eyes appear near the middle of the lorica. Found, 



