14 Fishery Board for Scotland. 



were captured in May in the crab creels at the Bay of ^igg bore eggs 

 which had been lately extruded. The mass of eggs was of a bright orange 

 colour : it is hidden by the abdomen. 



Some crabs which were captured in June 1909 survived till the 

 following spring. They had by then lost most of their eggs, and although 

 some eggs hatched, the larva? wei'e not secured. 



I have therefore been indebted to !Mr. Waddington for specimens of the 

 I. Zaea stage. Mr. Waddington had had a berried crab in confinement for 

 three months when it died on January 1st. " The eggs were removed, and 

 two months later successfully hatched." 



Megalopa which have been ascribed to this form were obtained bv the 

 Garl<ind in May 1900. The eggs, therefore, hatch comparatively early in 

 the year. 



/. Zoea, fig. 73 ; Abdomen, fig. 77 ; Telson, fig. 70 ; Cephahc Eegion, fig. 75. 



In general structure the Zoea of this species recalls that of the Zoea of 

 PortumL-s, in that it has a ro5ti"al, dorsal, and two lateral spines on the 

 cai-apace (fig. 78). It is, however, krger than the I. Zoea of the three 

 species of Poriunus dealt with here. It is at once distinguished from 

 Portunus in all its stages by the fact that the rostral and dorsal spines 

 are serrated. These spines are, moreover, practically straight. The 

 " branchiostegal tooth'" is present. 



The third, fourth, and fifth abdominal segments (fig. 77) have long 

 spines projecting from then' hind borders. 



The seii'^ted branch of the antenna reaches to about the tip of the 

 rostral spine; in the specimen drawn it projected a little beyond that 

 point. The serrations on the rostral spine increase in size from the 

 base towards the tip. The teeth on the doi-sal spine are much smaller than 

 those on the rosti-al spine. The exopodite-s of the maxillipedes had four setae. 

 The hind free border of the carapace bore three hairs, two of which at 

 least were plumose. 



Studs are present on the second and third segments of the abdomen. A 

 pair of hairs was found on the dorsum of the first to fifth segments. 



The narrow telson (fig. 70) is noteworthy. The prongs are minutely 

 serrated. 



Colours of Preserved I. Zoea. 



The retinal region of the eye is a dark brown, almost black in some 

 specimens. In the thorax there is behind the eye some deep amber 

 pigment. On the abdomen the pigment is a pale brown with red spots. 

 To the naked eye the Zoea has an amber colouration, generally all over, 

 certainly in the thorax, and often in the abdomen also. 



Later Stages of Zoea. 



The later stages were procured by means of the tow-net. The various 

 Zoese and the Megalops which were obtained in the plankton were readily 

 recognised as belonging to one species by their characteristic pigmentation 

 (fig. 1). This species is, I consider, Htjos areiieus. The plankton Zoese 

 agree closely in structui-e with the Zoeae of that form. 



Colours of Plankton Zoem when Alive. (Fig. 1.) 



The chief colour in the thorax was chocolate. Some had dark brown in 

 the cephalic region. A luminous band, gold or silver in appearance, was 

 present across the dorsum just behind the eyes. Posterior to that there 



