SPECIFIC CHARACTERS 473 



a table showing the recorded occurrences of shoals of Grimothea in Otago Harbour, 

 New Zealand, by months from 1898 to 1924 inclusive, from which it appears that they 

 occur throughout the year, but are most frequent during the southern summer. He 

 says, " It will be seen that they are practically always present during December, January 

 and February, but the extent of the shoals varies considerably from year to year. They 

 have been exceedingly plentiful during 1923 and 1924. When the spring shoals make 

 their first appearance the individuals are nearly transparent, the eyes and a red spot on 

 the carapace being the most prominent features ; but they grow very rapidly, and the 

 colouring becomes a more intense red as time goes on. By the beginning of December 

 the whole of the body is a brilliant red, with a very much darker spot on the carapace ". 

 Most of the specimens of M. submgosa and M. gregaria in the Discovery collections 

 were taken during the third quarter of the moon (21 to o days of age) ; but no lunar period 

 of swarming is indicated, as the specimens from St. 67 were taken when the moon was 

 12 days old, while Captain Fagerli says that the shoals of Grimothea and also of adult 

 M. gregaria off the coast of Patagonia were seen practically daily from January to May. 



CHARACTERS SEPARATING MUNIDA SUBRUGOSA AND M. GREGARIA, 

 AND THEIR POST-LARVAL STAGES 



M. subrugosa and M. gregaria are distinguished from each other by a number of 

 characters which were clearly defined by Lagerberg (1906, p. 6). They are— the shape 

 and direction of the rostral spine ; the shape of the carapace and degree of development 

 of the spines at the antero-lateral corners of it ; the length of the eyestalk and shape of the 

 cornea ; the shape and spinulation of the merus of the chelae ; the form of the endopodite 

 of the external maxilliped ; and the shape of the abdomen in cross-section, and its 

 spinulation. These differences are not particularized here as they are given in detail in 

 parallel columns by Lagerberg, but figures illustrating them are appended (Fig. 1). The 

 most obvious distinction between the two species is, however, in the form of the eyes, 

 and by this character alone they can be readily distinguished. In M. subrugosa they are 

 directed forwards and are short, but with a large cornea, and in dorsal view with a 

 strongly concave dividing line between cornea and stalk (Fig. 1 c). In M. gregaria they 

 are directed outwards and the whole eye is distinctly longer, but the cornea is smaller 

 and the line of junction between cornea and stalk is nearly straight (Fig. 1 c'). Dr Kemp 

 records the following note on the colour of the species (St. 51): " In M. subrugosa the 

 carapace is pale reddish brown throughout, with the transverse ridges slightly darker. 

 The central rostral spine is reddish, but the two lateral spines white. The eyes are 

 directed forwards in life, with the upper surface of the eyestalks white. The chelipeds 

 have a conspicuous dark brown patch at the base of the fingers, the finger tips and the 

 dactyli of all the walking legs being white. The large spines are everywhere white at the 

 tip and very dark brown at the base. M. gregaria is very dark brown throughout, often 

 with a bluish tinge on the back of the carapace and chelipeds, and entirely without the 

 diversity of colouring seen in M. subrugosa. In life the eyes are directed outwards". 



