242 DISCOVERY REPORTS 



there, as given by Matthews (1932), must be borne in mind. That M. gregaria inhabits 

 the shore waters of the Magellan Straits and the complicated channels of the adjacent 

 regions is well known from the observations of previous expeditions in addition to 

 records obtained by the R.R.S. 'Discovery' and 'William Scoresby'. The only occur- 

 rence of note lying offshore^ is in an area running east-south-east from Cape Blanco. 

 The numbers taken at the stations in this area are few and indicate a very meagre 

 population. 



Depth is probably the limiting factor in the distribution of the benthic adult ; but it 

 must be borne in mind that the adult stage may lead a pelagic life. Matthews (1932) 

 gives Young's (1925) limit of 60 fathoms (130 m.) as the greatest recorded depth at 

 which the adult is found. Only three or four stations with a greater depth than this 

 have yielded M. gregaria in this survey, but considering the habits of the animal it is 

 difficult to know with certainty whether the specimens were actually taken on the bottom 

 or at intermediate depths as the net was on its way to the surface. The greatest possible 

 depth at which adult M. gregaria might have been taken was at St. WS 783 with a depth 

 of 159 m. 



The Grimothea stage of M. gregaria, which is discussed in the following section, is 

 usually found in the proximity of land, 60 miles from the Falkland Islands shores at 

 St. WS 100 being the greatest distance out to sea at which it was taken, with the excep- 

 tion of certain records discussed below. 



SWARMING OF THE GRIMOTHEA STAGE OF 

 MUNIDA GREGARIA 



Matthews (1932) has discussed the Grimothea stage of M. gregaria and its relations 

 to the adult at some length. He also remarks upon its swarming habits and quotes from 

 many accounts of old voyages to show how this feature has been remarked upon by the 

 explorers of these regions from the earliest times. Such of these records as can be 

 plotted on the chart show that none occur far from land, but some are placed very much 

 farther north than any of our observations. 



On January 30, 1932, the R.R.S. 'William Scoresby' met with many swarms of the 

 Grimothea stage over an area some four miles in length, the swarms being so dense as to 

 impart a reddish tinge to the colour of the sea. This area of shoals was situated about ten 

 miles distant from the Eddystone Rock, East Falkland, and close to the position where 

 shoals were encountered by the R.R.S. 'Discovery' on May 4, 1926. 



Whilst these shoals were under observation by the R.R.S. 'William Scoresby' Mr 

 E. R. Gunther made the following note: "The patches were either spherical or sub- 

 circular suggesting a compact swarm of bees, or were extended into bands of irregular 

 width. One or two feet to three or four feet was the diameter of the smaller patches, 

 but whereas a swarm of bees is very dense and surrounded by wanderers, these swarms 

 had a well defined edge and were less dense". This description is interesting because it 



1 In addition there are the following three isolated records; at St. WS 761, two specimens, at St. WS 771 

 six specimens, at St. WS 791, one specimen. 



