162 MR. G. C. BOTJENE ON THE 



Nat. Moscou, 1833, p. 200), and has been further described 

 by P. Gervais (Ann. de Sc. Nat. ser. 3, t ii.), M. Fabre 

 (Ann. de Sc. Nat. ser. 5, t. vii.), Grriffitb (Animal Kingdom, i. 

 p. 135), and by C. L. Koch (Myriapoden, 1863). More recently 

 Mr. A. Gr. Butler has contributed largely to our knowledge of 

 the genus ("A Monographic Eevision of the Grenera Sphcerotlie- 

 rium and Zephronia^' Proc. Zool. Soc. Lend. 1873 ; Ann. &Mag. 

 Nat. Hist. xiv. 1874, p. 185 ; Trans. Entom. Soc. 1875, p. 165); 

 and Karsch has drawn up a new classification of the group, 

 founded on the differences occurring in the genital orifices of the 

 females (" Zur Formenlehre der pentazonen Myriapoden," Archiv 

 fiir Naturgeschichte, 1881). 



These authors confine themselves principally to a descrip- 

 tion of the external features of the animals, and to the establish- 

 ment of specific distinctions. I have not been able to find a full 

 account of the structure and anatomy of the genus. Unfortu- 

 nately the specimens in my possession, consisting of several indi- 

 viduals, both male and female, of the species SphcerotJierium oh- 

 tusiim and S. retusv/m, are so badly preserved, that I am unable 

 to give a complete account of their structure ; but I have been 

 able to make out a few points which will, I think, be of interest. 



The Sphcerotheria belong to the order Diplopoda, and the family 

 GrlomeridsB. Viewed from above, the general shape of the body, 

 when the animal is extended, is that of an ellipse. The dorsal 

 surface is convex, the ventral surface flattened or rather concave. 

 The head, viewed from the front, is subtriangular in shape, and 

 bears a pair of lateral aggregate eyes, beneath which are the deep 

 fossae in which the antennae are lodged. The head is succeeded 

 by a small nuchal plate, and this is succeeded by twelve segments. 



The tergites of the body are composed of half -rings of very hard 

 and dense chitin connected together by soft skin : when the 

 animal is extended, these overlap one another to a considerable 

 extent. The last tergite is produced laterally and posteriorly, 

 so as to form a complete shield with an evenly rounded thickened 

 margin covering the posterior end of the body. The lateral mar- 

 gins of all the tergites are produced ventrally, and are inclined 

 slightly backwards. 



The first tergite is larger than its successor, and its lateral 

 margins (pleura) are produced into strong, backwardly curved 

 processes, which overlap the two succeeding segments. When 

 the animal is rolled up, the head and posterior end of the body 



