466 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1909. 
or unfamiliar; on the contrary, many people, including the bathers on 
the Breton coast, are acquainted with the creatures that I am going 
to discuss, which are commonly 
called by the name of sea-spiders. 
These self-disguising Crustacea, 
although they belong exclusively 
to the rather restricted group of 
Brachyura Oayrhyncha, are very 
common, not only along all the 
European coasts (of the Mediterra- 
nean, the English Channel and the 
Fic. 1.—Disposition of the dorsal hooks 
in Maja verrucosa M. Edw. (Only Fic. 2.—Second left foot, outer side. 
the right side is completely drawn.) (Hyas araneus L.) 
Atlantic as far as Spitzbergen and Greenland), but also along the 
coasts of the Far East and southern Asia (Japan, Celebes, Java, 
Bengal, India, etc.), in the Pacific along the coasts of Tasmania, 
Australia, and New Zealand, and along the coasts of 
of South America (Peru, Chile, Cuba, Brazil, etc.). 
Of this group there are more than 70 species be- 
longing to 38 genera and 4 families. 
These Crusta- 
Fig. 3.—Group of 
hooks on a dorsal cea, ay. h 2 S e 
tubercle. (Hyas strange habits 
as impressed me 
forcibly during the very interest- 
ing dredging that we did in the 
vicinity of the Balearic Islands on 
board the Roland, of the Arago 
Laboratory during the month of FG: 4.—Vertical section made through a 
; : aos dorsal hook and the adjacent parts of 
August, 1903, form a quite distinct the carapace. Beds of chitin, chitog- 
group, possessing extraordinary enous epithelium and conjunction tis- 
: : : sue. (Hyas coarctatus Leach.) 
morphological adaptations which 
are not found elsewhere. A Swedish naturalist, Carl Aurivillius, has 
made an elaborate study of these adaptations, and it is from his work 
that I have taken the few drawings here reproduced (figs. 1-7). 
* The list published by C. Aurivillius gives only 66 species, but it is far from 
complete, not containing, for example, a form so common as Maja squinado 
Latreille. 
°C. Aurivillius: Die Maskirung der Oxyrrhynchen Dekapoden durch beson- 
dere Anpassungen ihres Kérperbaues vermittelt. Hine biologisch-morphologische 
Studie. Svenska Vet.-Akad. Handl., bd. 23, Stockholm (1889). 
