14 THE P.OTIFEKA. 



shows the chief longitudinal muscles. 'J'he ovary ifig. 2a) is verv laigc, and lias lai<'e 

 germs: a maturing ovum is visible iu fig. ii. A large nervous g'anglion of Notommatan 

 type stretches back from llie corona to the dorsal surface and bears a large red eye. 1 

 failed to find any antennae. The male is unknown. 



Length, j\ inch. Habitat. Near Birmingham (T.B.j : rare. 



Family X. NOTOMMATAD^. 



[Corona obliquely transverse ; ciliary wreath of interrupted curves and clusters, 

 usuallij tt:ilh a marginal wreath surrounding the buccal orifice ; trophi forcipate ; foot 

 furcate. 



The Rotifera associated in this family may be considered the most tyjjical repre- 

 sentatives of the whole class. They are permanently free, never affixed to other objects, 

 never to each other in clusters. Their bodies are not inclosed in tubes ; their integu- 

 ment is more or less flexible, never hardened into a shelly mail. The body is generally 

 cylindrical, with a length twice or thrice the diameter : the front does not expand into a 

 flower-like disk, but is usually convex, often with a flat versatile face, inclined down- 

 wards (supposing the animal to be crawling), beset with strong vibrating cilia, so arranged 

 that their combined action produces two vortices, one on each side of the head. The 

 posterior extremity bears a foot of several diminishing joints, capable, in a slight degree, 

 of telescopic inversion ; and the last of these bears two diverging toes, chitinous in 

 structure, used for support and locomotion. 



The trophi are well developed, all the seven constituent elements — the labrum, the 

 two mallei, the two iticus-rami, the fulcrum and the labitim — corresponding homo- 

 logically to the labrum, the 'mandibles, the maxilla and the labium, of insects,' being 

 present, in relative proportions. The mastax is so placed that the jaws can be freely 

 protruded from the buccal orifice, as has been seen in most of the genera, and used, 

 forceps-like, to slit the cells of Alg£e, to nibble the flocculent matter which grows on 

 vegetable stems, or to seize, retain, and devour active animalcules. 



Some of the genera possess a singular apparatus for suddenly augmenting locomotion, 

 in the form of a pair of organs (auricles), ordinarily concealed, which can be thrust out 

 in an instant, by eversion of the skin. The surface which is tlien external is clothed 

 with cilia, dense, vigorous, and capable of producing ample vortices in the water. 



The Notommatadm are the most highly organised of all Rotifera ; the most sudden, 

 varied, and energetic in their motions ; most highly endowed with external sense- 

 organs ; most predatory ; most nearly approaching to the Articulate classes, not only in 

 their manducatory organs, but also in their skin usually firm, elastic, capable of being 

 thrown into transverse folds, or sub-articulations, more or less permanent. If not the 

 most beautiful, they may claim to be the most interesting ; best repaying investigation, 

 while they present the greatest difficulties to tlie student. As this must be considered 

 the central or typical family, without adopting all the fancies of the Circular theories, 

 we may suggest that the relation between the genus Furcularia and the Loricata, 

 through Diaschiza, is very close : that Proales, with its long prone face, leads to the 

 Bdelloida through Adineta : that the skipping species of Furcularia, as lomjiseta and 

 aiqualis, look towai'ds the Scirtopoda : and that in the mucous investiture common in 

 the genus Copeus, we perceive a reflection of the excreted tubes of the Bhizota. — 

 P.H.G.] 



' See my mera. "On Mand. Organs," Phil. Trans. 1855 p. 449. 



