ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



321 



firmly and because they accumulate dehris on the short hairs which cover 

 the abdomen and caudal appendages. They are rectal breathers. No 

 true or functional caudal gills are present, these being replaced by two 



Larva of Micrometrus Uneatus, with the mask shown on the right. 



caudal appendages which seem only to serve for defence. These parts 

 are readily surrendered by autotomy, as is probably the case in the 

 related Rhinocvphine larva. The " mask " is long and narrow. 



J. A. T. 



British Orthoptera. — W. J. Lucas {A Mo7iograph of the British 

 Orthojjtera, Ray Society, 1920, 1-261, 25 pis., 25 figs.). The author is 

 to be congratulated on the completion of this very welcome monograph, 

 which deals with thirty-one indigenous species and eight naturalized 

 aliens. The sub-orders include the earwigs, the cockroaches, the 

 crickets, the long-horned grasshoppers and the short-horned grass- 

 hoppers. The workmanship of the monograph is at a high level, and 

 there is a generous supply of illustrations. J. A. T. 



5. Arachnida. 



Sarcoptid Mite in a Cat. — Harold Cummings {Report Michigan 

 Acad. Sci., 1913, 15, 106). Note of occurrence of Notoedres cati 

 Hering, heavily infesting a cat at Ann Arbor, and causing loss of hair 

 over a large surface. The genus includes Sarcoptid mites infecting 

 cats and rabbits, but there seem to be few records of their distribution. 



J.A.T. 



Pygidium of Trilobites.— P. E. Raymond {Geol. Mag., 1920, 57, 

 22-5). The large pygidium is primitive and the small one is specialized. 

 The thorax grows through the degeneration of the pygidium, new 

 segments being pushed forward through the pygidium by those which 

 are added in the growing area immediately in front of the anal segment. 

 The free segments of the thorax become such by the breaking down of 

 a large pygidium, and a small pygidium is the result of the degeneration 



Y 



