FAUNA OF THE CRESS AND QADE. 335 



tightly together, like the jaws of a pair of pliers. The foot was 

 often moved to the right or left and allowed the rounded notch 

 at the hinder end of the lorica to be seen distinctly. When 

 swimming with their dorsal surfaces fully exposed, the character- 

 istic marks or milling, a little within and round the edge of the 

 nearly circular lorica, could be easily seen in some specimens, 

 but in others the milling was less distinct. The lorica itself 

 was colorless and very transparent, and, when the Rotifer was 

 seen in side view, its hook-shaped frontal hood was a con- 

 spicuous object. The length of the lorica was about t |q in. 



All the specimens were obtained in spring, summer, or early 

 autumn, chiefly from the Berkhamsted Castle moats, and the 

 pools of Langleybury and Parsonage Farm, Abbots Langley. On 

 July 21st, 1913, many specimens of this species were obtained 

 from the inner moat at Berkhamsted Castle. Many loricas 

 and numerous living specimens were obtained on May 12th, 



1913, from Langleybury Pool, and about the same time this 

 year, May 2nd, 1914, five specimens were taken from the same 

 pool. On March 24th, 1913, Parsonage Farm Pool yielded 

 some empty loricas only, some with remains of the foot 

 attached, but many living specimens were obtained from the 

 same pool on August 18th, 1913. There are parts of the water- 

 cress-beds, temporarily or permanently out of use and contain- 

 ing a miscellaneous series of aquatic plants, which yield some 

 interesting forms of life. In one of these disused parts near 

 Watford, a few specimens of M. solidus were obtained on 

 September 16th, 1913. A solitary specimen was obtained from 

 Chesham Road Pool on May 26th, 1914. This specimen was 

 not as clear and healthy looking as the specimens obtained from 

 the moat and the other pools mentioned above. 



12. Metopidia oxy sternum, Gosse. This species has been 

 obtained from Berkhamsted Castle moats and Kings Langley 

 Lodge Pool. So well-defined and peculiar is the form of 

 M. oxysternum that it can be identified at once. The specimens 

 which, owing to their free and energetic movements, best 

 showed the characteristic features of the species were obtained 

 on July 21st, 1913, from the inner moat, and on April 13th, 



1914, from Kings Langley; in the moat they were found 

 together with a much larger number of specimens of M. solidus. 



