4S J. Wood-Mason — On NepTiro'psis Stewarti. [No. 1, 



The flagella of the antennae are remarkably long and of excessive fineness 

 at their extremities. 



The basal joint of the antennules has its upper surface greatly inflated, 

 owing to the remarkable development of the auditory organ to which, in most 

 Podophthalmatous Crustacea at any rate,* this joint gives lodgment ; and the 

 almost globular appearance of the joint as seen from the side contrasts strong- 

 ly with the flatness of its upper surface in Nephrops or Astacus. Of the two 

 remaining joints of the antennulary peduncle, the first is short and cylindri- 

 cal, being less than half the length of the last which in Nephrops is short 

 and equal to that which precedes it. The peduncle terminates in the usual 

 manner in a double flagellum, the outer branch of which is conspicuously 

 stouter than its filamentous and cylindrical fellow, perceptibly compressed, 

 and thickly fringed below with short hairs along its distal third. 



The epistoma is much the same as in Neplirops, save that its posterior 

 edge is straight and presents two small tubercles which give it the appear- 

 ance of being slightly roundly-emarginate in the middle. 



The external maxillipeds and the parts of the mouth in front of them 

 are identical in structure with those of Neplirops. 



The eyes are completely rudimentary, neither pigment nor corneal mem- 

 brane being developed ; the peduncles indeed are present, but even these are 

 short, subcylindrical, mere aborted structures, concealed entirely from view 

 by the stout base of the overhanging rostrum ; in spirit they have become 

 perfectly blanched like the rest of the appendages, but in life the delicate 

 rose-pink coloration of the animal extended itself to their very tips. The 

 peduncles are far less conspicuous from the side view than represented in the 

 plate. 



The first pair of abdominal appendages^ those which bear the great 

 chel(E, are unfortunately absent, the specimen having lost its claws a consi- 

 derable period previous to its capture, as the presence of uncalcified reproduced 

 rudiments of these appendages indicates ; the other legs are smooth and 

 slender ; the second and third pairs are didactyle ; of these the former has 

 both its upper and lower margins, from the base of the carpopodite to the 

 extremity of the cHws, fringed with long hairs ; the latter, much the slenderer 

 as well as the longer of the two, has its propodite greatly elongated, and its 

 olaws only are ciliated. The fourth pair, the longest of all and ciliated only 

 on the outer face of the dactylopodite, and the fifth, about as long as the 

 second pair, are monodactyle, 



the ischiopodite. For the facts relating to the transformation of the embryonic exopo- 

 dite into the antennal scale of the Prawn pan ^^ass it with the budding out of the 

 flagellum and the abortion of the-endopodite, vide Fritz Miiller's admirable essay ou 

 the development of the Crustacea entitled *" Fiir Darwin," p 41, fig. 31. 

 ^ The caudal ear of My sis fornis an exception to this. 



