18 Fishery Board for Scotland. 



The pigmentation of this stage is similar to that of the I. Zoea. 

 A description of this stage has been given by Pearson.* 



/. Zoea. 



Pigmentation. — A yellow corpuscle is present on the hind dorso- 

 lateral and the hind lateral regions of the cephalothorax and on the 

 posterior lateral region of the second to fifth abdominal segment and telson. 

 Each yellow patch is accompanied by green, red (pnrple), and black 

 pigments. The dorsal and rostral spines and fork of the telson are 

 coloured red. The colours are shown in a sketch of this stage, published 

 in an earlier communication.t In this drawing short, very delicate 

 hair-like filaments are shown attached all over the integument. These do 

 not belong to the larva ; they are of secondary appearance, and may be of 

 fungoid origin. They are not present in the newly hatched Zoea, i.e., within 

 24 hours of hatching. 



To the naked eye the larva has a whitish appearance. 



The I. Zoese are brightly phosphorescent. 



Zoete which have been preserved in formaline are whitish or colovirless to 

 the naked eye. The eyes are reddish-brown. Those which have been pre- 

 served in alcohol have black (very dark brown) eyes. 



Structure of 1. Zoea. 



This Zoea has a dorsal, a rostral, and two lateral spines on the carapace. 

 The lateral spines are long (fig. 63a). The i-ostral spine is long and 

 straight and slightly bent upwards. In some Zoepe the dorsal and rostral 

 spines are a little bent at the point, but this may be due to handling. 

 No hairs were made out on the hind free edge of the carapace. A small 

 hair is, however, present on the carapace on each side of the base of the 

 dorsal spine. A slight " branchiostegal tooth " is present. This Zoea 

 has been described by several authors, and lately by Pearson, but, so far as I 

 am aware, detailed drawings of the appendages have not been published. 



The various appendages are shown in Plate IV. They conform closely 

 to such a type as Garcinus mcBnas. This is well seen in respect to the 

 mandible and first and second maxillse and two maxillipedes. The 

 antenna (fig. 66), however, is noticeable on account of the difference in 

 size between its two branches. The serrated branch is very much longer 

 than the jointed branch. 



The labrum (Ir., fig. 59) is covered with small teeth. 



In dissecting off" the appendages the second maxilla usually tends to 

 remain attached to the first maxillipede. The first maxilla may go either 

 with the mandible or the second maxilla. The lower lip is attached to 

 the sternum. The mouth marks the separation between the cephalon and 

 the thorax. 



The stalked eyes are shown in fig. 64. The torn edge, t., indicates where 

 the carapace was attached. 



Two views are given of the mandible. In fig. 52 it is seen from below, 

 and in fig. 52a from outside. The pUte {pi.) when seen from the side 

 resembles a tooth. A portion of the mandible is shown in fig. 50; 

 d. indicates the dorsal edge. 



The buds of the pereiopods {p.) are contained in a sac covered by a thin 

 skin (fig. 54). The pit is shown in ventral view in fig. 56. All the buds 

 were not visible ; ant. indicates the anterior edge. The skin covering the 

 pit may be a portion of the protozean cuticle which had remained attached. 



* "Memoir on Cancer pagurus." No. 16 Report for 1907 of the Lancashire Sea- 

 Fisheries Laboratory and the Sea-Fish Hatchery at Piel. Liverpool, 1908. 



t Williamson : " Contributions' to the Life-history of the Edible Crab (Cancer 

 pagxLrus)." l^th Ann. Report of the Fishery Board for Scotland, Pt. III., p. 76. 



