86 



Mr. A. Patience on 



T. sarsi. 



T. alhidus. 



Second pair of pleopoda of male. 



The terminal joint of inner ra- 

 mus forms a narrow folded plate 

 about twice the length of first joint, 

 and terminates in a corkscrew -like 

 point. 



The terminal joint of inner ra- 

 mus is comparatively much nar- 

 rower, more prolonged, being about 

 three times the length of first, is 

 contracted at a little beyond the 

 middle of joint, and is then pro- 

 duced to a straight needle-like 

 point. 



First pair of pleopoda of female. 



The inner ramus appears to be 

 comparatively larger, while the 

 outer ramus ia creuulated on the 

 inner margin. 



Seventh peroeopod of male 



Tbe meral joint is produced at 

 the base on the inner side to a 

 small dentifonn prominence. 



The meral joint has no denti- 

 form prominence. 



Antennas. 



The flagellnm is composed of 

 four articulations. 



The flagellum is composed of 

 three articulations, the middle joint 

 being: the longrest. 



The type of coloration in T. alhidus is not unlike that of 

 Trichoniscus pusilhts (Brandt). The lighter patches on the 

 back are of a golden-yellow colour, while the rest of the back, 

 the legs, and the antennas are diffused with light reddish 

 brown. The specific name, as Sars long ago pointed out, is 

 somewhat inappropriate. It is only specimens which have 

 been preserved in alcohol or formalin that show a white 

 colour. In the latter preservative, specimens lose their 

 pigment in a very few days. The specific name has evi- 

 dently misled the authors of ' The British Woodlice ' *, for 

 they state (p. 25), " From the first its white colour will serve 

 to differentiate it." 



The young, however, of T. alhidus on leaving the female 

 are pure white, with the exception of the eye, which has a 

 brilliant ruby tint. Shortly afterwards a diffuse light reddish 

 pigment is found on the back, forming slight ramifications on 

 each side of the segments. 



I think there can be little doubt as to the specific distinct- 

 ness of T. sarsi, and my opinion upon this point has been 

 endorsed by those two eminent carcinologists, Professor 

 G. O. Sars and Professor Malcolm Laurie, F.L.S., to whom 



* < The British Woodlice,' London, 1906. 



