26 MR. R. GURXEY ON THE [May 12, 



The basal part between the eyes is broad, and distally it coii- 

 tracts suddenly and tapers to a sharp point. In one example this 

 narrow part was found to be bifid down to its base, though the 

 postlarval form moulted from it was in no way abnormal. The 

 general form of the carapace is unaltered. 



In the abdomen the laterodorsal spines of the fifth segment are 

 longer, and end in a sharply down-curved hook. I have drawings 

 of a larva taken in July 1901 at Plymouth, in which this spine 

 is of an unusual length, being about two-thirds the length of the 

 long sixth segment. 



The tail-plate, now distinctly separated from the sixth segment, 

 is much narrower at the end compared with its total length, 

 and its sides are not straight, but conspicuously curved. There 

 are still seven setse on each side of the posterior margin, but a 

 short way up the side on either hand is a minute knob, repre- 

 senting the eighth seta found in other species. 



The antennae (PI. VI. fig. 14) are now still more elongated, the 

 flagellum of the second antenna now considerably exceeding the 

 scale in length. The latter has now a large number of marginal 

 setfe. 



Such changes as have occurred in the maxillfe are unimportant. 

 In the maxillipedes five joints can now be detected in the endo- 

 podite of the second and third, but that of the first remains to all 

 appearance three-jointed. All the thoracic appendages, as well 

 as the pleopods, are now present, and have the usual Crangonid 

 form. The first five pairs of thoracic appendages have exopodites. 

 As regards the gills, not having any example of stage iv., 1 cannot 

 oflTer any observations as to theii- origin, but in the last stage 

 they are well developed, and the five posterior pairs are distinctly 

 pleurobranchs. In this respect C. fasciatus and also C. tri- 

 sjmiosus difier from C. vulgaris, in which Williamson describes 

 the gills as having the position of arthi-obranchs at this stage. 



The foregoing account shows that the larva of C. fasciatus is 

 readily distinguishable from all other Crangon larvee yet described. 

 The larva most closely approaching it seems to be one described 

 by Glaus (1861, taf. ii. fig. 1). This larva possibly may be that 

 of C. sculptits, and differs from that now under consideration in 

 its much more compact body and the relative length of its dorsal 

 abdominal spines. The length of the antennee, slender body, and 

 shape and size of the abdominal spines are distinctive of the larva 

 of C. fasciatus. 



The next moult leads at once to the postlarval stage, in which 

 the adult form is assumed. The young shrimp has the broad, 

 depressed form of the adult, with its characteristic square rostrum 

 and bright, somewhat banded, coloviring. The only important 

 point of diflierence lies in the sculpturing of the carapace. In this 

 first postlarval stage the carapace is smooth except for a short 

 anterior median ridge, with two or thi'ee blunt prominences. 



