236 DISCOVERY REPORTS 



curve of this first-year group probably indicates a moult to the greater length of 1 1 -5 mm. 

 actually in progress. Again, no growth seems to take place during the winter months 

 and the September first-year group is dispersed about a mode slightly above ii-o mm. 

 corresponding to that indicated in May as an asymmetry on the upper limb of the main 

 curve. 



The records of the older groups in the male population are inadequate or absent, and 

 no satisfactory account of the later growth can be deduced from them. The general 

 growth no doubt closely follows that suggested above for the female. 



I wish here to acknowledge the help given to me by Mr T. Edser, of the Ministry of 

 Agriculture and Fisheries, whilst preparing this account of the growth of the two species 

 and particularly to thank him for the idea embodied in the circular graphs of Figs. 9 

 and 12. 



EPIZOA AND PARASITES 



The two species of Munida, in common with many other members of the Decapoda, 

 often carry on their exoskeleton an epizootic fauna. Large and obviously older speci- 

 mens were those most commonly infected. The commonest epizoa are Serpulid Poly- 

 chaetes resembling Spirorbis. At times these occur very extensively, not only on the 

 carapace, but on the tergites and pleura of the abdominal segments, on the legs, 

 especially on the chelate limb, and even on the ocular peduncle. 



M. gregaria was found carrying growth of a Polyzoon, Alcyonidiiim sp. This occurred 

 most frequently on the tergites and pleura of the second to the fourth abdominal 

 segments, where flexion of the abdomen occurs ; but on some specimens the incrusta- 

 tions spread over the carapace, on the legs and in one case extend even on to the eyes, 

 obscuring the pigmented corneal portion to such a degree as to interfere with vision. 

 A Vorticellid was seen on the limbs of immature specimens of both M. gregaria and M. 

 subrugosa. 



The two species of Munida both harbour a Bopyrid parasite, Pseudione galacanthae, 

 Hansen, which takes up its position in the branchial chamber. In all except the most 

 recently infected individuals the presence of the Isopod is displayed by the bulging 

 carapace and branchiostegite, a deformity which in older specimens assumes no mean 

 proportions. 



Pseudione galacanthae was first found in Galacantha diomediae var. parvispina, Faxon, 

 in the Gulf of California (Hansen, 1897). It was recorded from Munida subrugosa taken 

 on the east coast of Patagonia by Richardson (1904), and it has also been obtained from 

 Munida quadrispina, Benedict. A rather larger size is attained by specimens from 

 the two species of Munida considered here than by those first described by Hansen and 

 obtained from Galacantha diomediae. The slight asymmetry shown in Hansen's figures 

 of the type is still less marked in the specimens before us. P. galacanthae was always 

 found with its head pointing posteriorly with regard to the host and with the long axis of 

 the body lying in a diagonal position so that the anterior part of the body was more 

 ventral in position than the mesosome. 



