404 CONTRIBUTIONS TO MARINE BIONOMICS. 



male." Ou account of the presence of these spots Eisso named the 

 species Portunus higuttatus, 2}ort2ine a deux taches, fortune himacuU 

 (p. 25). 



Costa, on the other hand (Addizioni, 1853, p. 11), describes the colour 

 as " livid olive-brown tending towards purple ; that of the feet and of 

 the inferior face more pallid. In fresh specimens one may sometimes 

 observe two rose-coloured spots in the middle of the carapace, which 

 vanish after death." 



Of my own specimens the larger one was of a uniform dull greenish 



yellow colour, the smaller one having the carapace and basal joints of 



the legs absolutely white, and the two terminal joints of the four 



posterior pairs of thoracic legs coloured pale brown and amethyst-violet. 



No reddish spots were visible in the living specimens. It is possible 



that these spots are only to be observed in the breeding season, and 



that they are due to the colour of the reproductive glands showing 



through the carapace. Such a phenomenon is at any rate described by 



Eisso for Bathyncctes longipcs. He states (1816, pp. 30, 31): "La 



femelle, dans le temps des amours, est ornee de deux grandes taches 



d'un rouge fence sur la partie anterieure du tet." The eggs of the 



latter species are described as "d'un rouge aurore," which would 



sufficiently account for the red colour of the ovarian regions before 



deposition of the ova ; those of P. nasnius are described as " d'un 



jaune dore." Eisso states that the eggs of P. nasutiis are laid in May 



and August. 



5. Sand-burrowing Habits. 



The habits of Portummis nasidus have hitherto been very imperfectly 

 described. Eisso (18 IG, pp. 25-31) states simply that at Nice the crab 

 inhabits "la region des polypiers corticiferes " (p. 25), or "la region des 

 coraux" (p. 31). Latreille's specimen (1825, p. J 51) was obtained by 

 D'Orbigny on the coast of La Vendee, which probably implies a sandy 

 habitat, especially as Latreille's specimens of " Platyonichus varicyatiis " 

 {Poi'tumnus latipcs) were obtained by the same naturalist on the same 

 coast {Nonv. Did. d'lIisL Nat., 1818), and the latter species is known 

 to have sand-burrowing habits. 



My own observations are, however, unequivocal. The specimens 

 were found burrowing in coarse shelly gravel, and when the crabs were 

 introduced into an aquarium containing a deep layer of the same gravel 

 they were observed to burrow into it at once with extreme agility until 

 their bodies were completely covered to a depth of an inch or more. 

 The act of burrowing is effected by means of the hinder thoracic legs, 

 as is usual among Portunids. The crabs can also burrow in fine siliceous, 

 sand. 



When imbedded, P. nasutus seems always to adopt a nearly horizontal 



