292 MR. W. E. COLLINGE ON THE VAEIATION OF THE 



The 2nd Maxillce. — In eight specimens from Northern India this appendage 

 had the form shown in figure 29, whilst in six examples obtained from 

 different parts of the British Isles the variation took the form shown in 

 figure 30. 



7, Armadillidium vulgare [Latr.) Milne-Edwards. (PL 21. figs. 31-33.) 



Fifty-one examples of this species were examined and three variations 

 observed, viz., one in the mandibles found twice, and one in each of the 

 maxillse, each of which occurred three times. 



The Mandibles. — A slight modification was noticed in two specimens where 

 the teeth were shorter than usual (fig, 31). 



The 1st Maxillce. — The outer lobe terminated in a strong spine^ rather 

 shorter, however, than in typical examples, and this was followed by five 

 very short, tooth-like spines ; the inner lobe terminated in a sharp, short spine 

 on the outer side and two small blunt spines on the inner side (fig. 32). 



The 2nd Maxillw. In the typical form the terminal portion externally is 

 produced into a tooth-like piece whilst internally the terminal portion is more 

 or less flat or plate-like. Sars's figure (5, pi. (S2, fig. ni) is an excellent one. 

 In the variation noted in three examples, both the internal and external 

 terminal jjortions were flat and rather stouter in build. 



III. Summary and Conclusion. 



1. Four-hundred and thirty- eight specimens have been examined embracing 

 seven species referable to six genera and four families, and one-hundred and 

 ten individuals exhibited variations. 



2. Of the one-hundred and ten individual variations thirty-one occurred in 

 the form of the mandibles, twenty-eight in that of the 1st maxillas, twenty-one 

 in that of the 2nd maxillse, and thirty in the form of the maxillipedes. 



3. The conclusion arrived at, after carefully examining and considering, the 

 above mentioned variations, is, that the oral appendages are subject to a 

 considerable amount of variation, and for purposes of specific distinction are 

 not of the value generally supposed, and certainly not so constant as the form 

 of the head, the mesosomatic segments, the antennse, the telson, uropoda, and 

 thoracic appendages. That they may serve to characterise the larger divisions 

 is possible. 



Bibliography. 



1. BuDDE-Lui^D, G. — A Revision of Crustacea Isopoda Terrestria. 1899- 



1904, Pts. i-iii, pp. 1-144, pis. 1-10. 

 3. Wissenschaftliche Brgebnisse der Schwedischen Zoologischen 



Expedition nach dem Kilimandjaro, dem Meru und den umgeb- 



enden Massaisteppen Deutsch-Ostafrikas, 1905-1906. Crustacea : 



Isopoda. 1910, pp. 3-20, pis. 1, 2. 



