16 Fishery Board for Scotland. 



The coxopodites of the second, third, and fourth pereiopods have lai-ge 

 teeth it., fig. 74). A large tooth is also present on the ischiopodite of the 

 second pereiopod. The armature of the legs is not shown : it consists of 

 hairs and short toothed spines. The abdomen is narrow, and is furnished 

 with five pairs of plumose swimmerets. 



The Megalops when it swims tucks its pereiopods over the carapace, and 

 swims forward. It also walks. A number of Megalopa had cast on 14th 

 June into the first young stage. More ecdyses were found than there were 

 of first young stage crabs. The remains of some of the latter were found 

 more or less eaten, probably by Megalopa. 



First Young Stage. Figs. 76, 72. 



The first young stage is a little crab having some points of resemblance 

 to an adult Hyas. The rostrum is forked. The abdomen is applied to the 

 thorax ; the pleopods are still large, but unprovided with setfe. The 

 carapace is adorned with hooked hairs similar to those on the adult. The 

 hairs have been omitted from the right hand branch of the rostrum in 

 figs. 76 and 72. 



There is an elaborate toothed process of the carapace at the posterior 

 corner of the orbit. 



The crab is of a sandy colour. Large stellate black pigment corpuscles 

 are present just behind the rostrum. One is situated about the middle of 

 the carapace. The crab picks ofi" and eats the debris {fine sand and diatoms) 

 which becomes attached to its carapace and limbs. One was observed to 

 eat a copepod. 



This stage does not swim. 



The plankton Zoese and Megalopa all belonged to one species. I have 

 regarded that species as being Hyas areneus, but that diagnosis is open to 

 question. 



Parasite of Hyas areneus. 



The advilt Hyas, captured in the Bay of Nigg and in other localities, 

 were often infected by very long nematodes (fig. 79, n. and w^). The nema- 

 tode is coiled round and between the organs. There are usually two worms 

 present, one situated on each side. They are seen as soon as the carapace 

 is removed. 



A crab died in the Laboratory on August 3, and at the same time two 

 long nematodes were found to have issued from it. The woi-ms, which 

 wriggled about in the water, were white, except for the translucent 

 extremities. When the Hyas was opened the organs, liver, and ovary 

 appeared to be quite healthy, Next day a quantity of white spawn had 

 been deposited on the bottom. One worm was partly emptied of spawn. 

 At one part its skin was translucent and shrivelled ; at another part the 

 white ova, instead of forming a continuous streak, were in pieces. 

 The eggs examined on August 4 measured 0-5 mm. in diameter. The egg 

 (figs. 68 and 68a) has two investments. On the outside there was a layer 

 of protoplasm which was in some ova extended into little radiating pro- 

 cesses. The following day they showed the condition seen in fig. 69. 

 Some of the spawn still lay on the bottom on August 6. No development 

 seems to have taken place. 



Eupagurus hernliardus, L. 



The eggs were found to have hatched on June 15. 



The first Zoea stage (fig. 6) shows a large silvery-luminous yellow 

 corpuscle in the dorsum of the cephalothorax. The red ochre pigment is 



