203 anceiuj:. 



He also notices " the shortness of the pleon, and the 

 smalhiess and more equal size of the pereiopoda." The 

 three organs on the right-hand side of the above wood- 

 cut represent first, to the left, the four-jointed outer foot- 

 jaw, of comparatively very small size, the basal joint 

 being large and curved, and the apical one very minute. 

 The middle, scale-like, exarticulate piece clearly repre- 

 sents the scale, which is the homotype of those belonging 

 to the incubatory pouch ; and the large five-joint organ 

 to the right is one of the inner pair of the foot-jaws 

 which, in the female of A. maxillaris , is comparatively 

 very minute, and which we have failed to discover in 

 the female of A. Halidaii. The organ represented on 

 the left side of our woodcut is the outer foot-jaw 

 seen in a different position, in which the minute apical 

 joint is not visible. These specimens were forwarded 

 from Banff" by Mr. Edward, in whose honour they 

 were specifically named. One of them was charged 

 with young, and a figure of one of the larvae extracted 

 from the incubatory pouch is represented in the left- 

 hand figure of the woodcut upon p. 177. '' It is a 

 remarkable fact," observes the author in introductory 

 remarks on the genus, " that in the young the organs 

 generally bear a closer resemblance to those of P. cceru- 

 leata than to those of their own parent species." We 

 are now able to account for this remarkable fact, from 

 having learned that P. cceruleata, which we then con- 

 sidered as a distinct species in a fully developed con- 

 dition, is only a full-grown larva of the preceding 

 species. 



Our knowledge of the present species must of course 

 be considered as imperfect until its legitimate male is 

 discovered. 



