fold or a pair of lateral hollows in which a pair of organs known as scapliorinatliites 

 (to be described along with the appendages) lie. 



We shall find, on examining the appendages, that the head consists of six 

 segments fused together, and the thorax of eight. Add to these the seven 

 abdominal segments, and we get twenty-one as the number of segments that 

 make up the body of Nephrons. 



It has been questioned wlietlier the last segment of the abdomen, known as the telson, is really 

 a somite, since among other reasons it carries no appendages. But it seems probable, from the 

 form and sculpture of this part of the body in certain deep-sea Decapods— notably the J? rf/o)U(f« 

 and some GalatheiJse — that the telson consists of a modified somite and a pair of biramous appeud- 

 iiges all fused together. Moreover it is traversed by the intestine. 



It has also been objected that the eyes are not truly homulogous with appendages and that 

 the part from which they spring is not therefore a somite. But apart from other considei-ations 

 tlie fact that, as a "substitution" abnormality, the' eyestalk may be replaced by a recognizable 

 appendage, is enough to dispose of this objection. 



On the other hand it has been argued that the pair of fleshy lobes that form the posterior 

 boundary of the mouth-slit and are known as the metastoma or loiver lip, .are true appendages 

 and therefore represent an additional somite ; though there are no facts to support this view. 



The cephalothorax is held together not merely by fusion of the sterna and 



epimera of its constituent somites, but also by an internal lattice-work of thin 

 hard obliquely-transverse partitions known as apodemes. 



Although the apodemes are internal and serve to protect and support the 

 viscera as well as to give attachment to muscles, they are merely infoldings of 

 the cuticle of the constituent sterna and epimera. They are only found behind 

 the mouth and in the ventral half of the somites. 



Before further considering the segmentation of the cephalothorax it is 

 necessary to speak of the appendages. 



2. Of t]te Appendages in general. 



The recognizable appendages of Nephrops andamanica are twenty pairs. 



The first six pairs belong to the head : three of them lie in front of the 

 mouth and are organs of the senses, while three are crowded together on either 

 side of the mouth and are biting and chewing organs, the last pair also 

 contributing to the respiratory mechanism. 



The next eight pairs belong to the thorax : the first three of them, which 

 are crowded together in close succession to the mouth-parts of the head, ari> 

 organs partly of manducation and partly auxiliary to respiration ; while the 

 other five are legs in the ordinary sense, though some of them are modified 

 for prehension, and most of them take a certain part in respiration. It is from 

 these 5 pairs of large legs that the name of the Order is derived. 



