4?8 DISCOVERY REPORTS 



is doubtless an adaptation to pelagic life; and he admitted that it may " be possible that 

 some of the newly hatched young pass to the surface and exist for a longer or shorter 

 period in the Grimothea state". Henderson named his specimens from Bass Strait 

 M. subrugosa var. australiensis ; he distinguished them by the large development of 

 spines and stated " in other respects this variety cannot be distinguished from the typical 

 form of M. subrugosa ; indeed on examining a series of the latter nearly all the above- 

 mentioned spinules can be made out in different specimens, though I have failed to see 

 any in which so many were present at the same time". 



A. Milne Edwards, in 189 1, in the report of the " Mission Scientifique du Cap Horn", 

 gave a full description of M.gregaria and stated that M. subrugosa was a distinct species, 

 basing his separation on several characters which depend on the size and sex of the 

 individual, and on the foliaceous external maxilliped of M. gregaria. 



G. M. Thomson in 1898 fully discussed the question as to whether Grimothea gregaria 

 is the young stage of M. subrugosa. He said, " Munida has the exoskeleton rather hard, 

 and exhibiting considerable complexity of imbricating scales and of spines on its surface, 

 but, with the exception of its softer and thinner texture, Grimothea has the same spines 

 and markings. The difference in the length and development of the external maxillipeds, 

 on which Leach founded the latter genus, and on which Miers and Henderson lay so 

 much stress, is after all a comparative one. In several large males of Munida the joints 

 all show the flattened and foliaceous form characteristic of Grimothea, as well as the 

 densely fringing setae, while in one large female the joints are completely foliaceous. 

 To show the relative lengths of the parts in the two forms, I append a table of measure- 

 ments of a few individuals taken at random The relative length of the body to that 



of the external maxilliped is about 5 to 2 in Munida and 5 to less than 3 in Grimothea. 



The sexes are usually present in about equal proportions in shoals of Grimothea Out 



of a large number of specimens of Grimothea all had the pair of spines at the side of the 

 median line of the second, third and fourth abdominal segments, said by Miers to be 

 characteristic of Munida. On the other hand, several male specimens of the latter wanted 

 the characteristic ' spine on either side of the middle of the gastric region ', while in some 

 females they were but slightly developed. Until, then, the life history of these crustaceans 

 is worked out I am inclined to treat Grimothea gregaria as merely a stage in the develop- 

 ment of Munida subrugosa". The specimens that he identified as M. subrugosa (adult) 

 were undoubtedly M. gregaria, hence the confusion. 



In 1902 Lenz recorded specimens of M.gregaria from the Patagonian region and stated 

 that he regarded M. gregaria and M. subrugosa as different species. In the same year 

 Hodgson recorded examples of M. subrugosa from Auckland and Campbell Islands and 

 said that "general opinion" did not support the view that Grimothea gregaria was the 

 young stage of M. subrugosa, though the only good character separating them was the 

 form of the external maxilliped. Benedict in 1903 stated that Grimothea gregaria was 

 the young stage of the bottom-living form which he called M.gregaria. But he was not 

 satisfied that the bottom-living form from the Cape Horn region was identical with that 

 from New Zealand waters, which he consequently listed as M. subrugosa. He did not, 



