698 



SYSTEMATIC HISTORY OF THE DfFUSOEIA. 



variable forms of one and tlie same 

 animal. 



S. mutica (Party). — Lorica toothless 

 both in front and behind, truncate pos- 



teriorly with obtuse angles. Transparent. 

 Eye red. Tail-flaps extend to the root 

 of the tail. 



Genus DINOCHAEIS (XXXIY. 454-456). — Eye single, cemeal ; foot 

 furcate ; lorica closed below, with a shai^) lateral margin, but unarmed at 

 both ends. The compoimd rotary organ has five or six muscles, and in two 

 species the foot two. An oesophageal bulb, with single -toothed jaws, is found, 

 except in D. tetractis, which Ehrenberg thinks has four teeth ; oesophagus 

 very short, alimentary canal constricted ; two oval glands exist in D. Pocillum 

 and D. tetractis. An ovary is seen in all, and a contractile vesicle at the 

 base of the foot in D. Pocillum. Traces of a water-vascular system are 

 perhaps to be seen in D. PociUum, though even here it is doubtful, for the 

 apparently tremulous organ just behind the oesophagus may be only a tre- 

 mulous condition of an internal fold of the stomach. The only evidences of a 

 nervous system are the eye and the long ganglion which supports it. 



DiNOCHAEis PociUum (TricJioda Po- 

 cillum, jNI.). — Lorica nearly cylindrical, 

 with a slight dorsal ridge; two long 

 spines at the base of the foot, toes three, 

 (xxxrv. 454, 455 represent this creature 

 in different positions ; and 456 the oeso- 

 phageal bulb.) Amongst Ceratophylla, 

 &c. 1-120". 



D. tetractis. — Lorica acute, triangular ; 



horns two, at the base of the foot ; toes 

 two. This species has longer toes than 

 the others ; and the body is comparatively 

 shorter. "With Lemnae and Ceratophylla, 

 1-120". 



D. pauper. — Lorica acute, triangular ; 

 horns two, at the base of the the foot, 

 scarcely perceptible : toes two, short. 

 1-120". 



Genus MONUEA (XXXIY. 457-459;.— Eyes two, frontal ; foot simple, 

 styliform. The lorica is somewhat compressed and open upon the ventral 

 siu'face : anteriorly is a hook-Kke process, which can be withdi^awn. In one 

 species, the vibratile organ has four to six muscular bulbs; in both, an 

 oesophageal bulb, with two-toothed jaws, a very short oesophagus, and a 

 simple alimentary canal with two spherical glands are observed; an ova- 

 rium, with a single large ovum, has been seen. The eyes are red, moveable, 

 and seated upon nervous masses. The species are not only difficult to di- 

 stinguish from each other, but also from the genus Colurus, — the toes of the 

 latter appearing single until pressiu-e is used. 



MoNUEA Colurus. — Lorica oval, ob- 

 tuse, obliquely truncated posteriorly, 

 eyes near to each other. Lorica 1-280". 

 Siberian specimens 1-400". 



M. cMcis. — Lorica ovate, anteriorly 

 acute, posteriorly obliquely trimcate ; 



eyes distant from each other; the ali- 

 mentary canal is often filled with green 

 matter.*^ They increase rapidly in glass 

 vessels, (xxxiv. 457-459 represent three 

 ■\dews of this animal.) Amongst Con- 

 fervae. Leno-th of lorica 1-288". 



The two species of Monurcc are referred by Dujardin to Colurus, or, to 

 adopt his appellation, to Colurella. 



Genus COLUEUS (XXXIV. 460-462).— They have two frontal eyes, a 

 furcate foot, and a compressed or cylindrical lorica. The lorica is said to be 

 open upon the under side (scutelhmi) ; a compound rotary organ is present in 

 all, over which projects a retractile frontal hook ; an oesophageal bulb with 

 two jaws, in two species with two or three teeth ; the oesophagus very short; 

 two species have a constricted stomach (Gasterodela), the others have a simple 

 ahmentary canal (Coelogastrica), aU with glands. The two red frontal eyes 

 are delicate ; in C. uncinatv.s and C. bicusjndatus they have escaped obsen'a- 



