84 IOWA STUDIES IN NATURAL HISTORY 



Length of carapace of larger $ on median line 53.5, extreme 

 width 71 mm. Length of smaller 9 20.8, width 24.4 mm. 



Approaches M. hispidus in its large size and general shape, 

 but the carapace is a little narrower, and the crenulation of the 

 prehensile edges of the fingers in the gape persists in the old, 

 while it disappears in old hispidus. 



Differs from all its allies in the arrangement of tubercles or 

 tubercles and spines on the posterolateral region. There is a 

 posterolateral spine in the young and middle-sized, which be- 

 comes a tubercle in the old ; it is situated not far behind the spine 

 at the lateral angle of the carapace, and forms the outermost of 

 a transverse row of three, which is subparallel to another row of 

 three tubercles. 



Barbados is the furthest east for this species ; it has been taken 

 at Porto Rico, St. Thomas and Venezuela. 



MiTHRAX (MiTHRACULUs) scuLPTus (Lamarck) 



Rathbun, Bull. U. S. F. C, vol. XX for 1900, part 2, 1901, 

 p. 71. 



Pillars of Hercules, English Harbour, Antigua; 14 5 6 9 (4 

 ovig.). 



English Harbour ; 1 5 . 



Pelican Island, Barbados ; 4 5 . 



Barbados ; under sea anemone ; 3 5 1 9 . 



M. sculptus is usually olivaceous, the color persisting in alco- 

 hol. The 4 specimens taken from under sea anemones are an 

 exception, as they are reddish brown, in alcohol. 



MiTHRAX (MiTHRACULUS) CORYPHE (Hcrbst) 



Rathbun, Bull. U. S. F. C, vol. XX for 1900, part 2, 1901, 

 p. 71. 



Pillars of Hercules ; English Harbour, Antigua ; 6 5 7 9 (4 

 ovig.). 



Ft. Barclay, English Harbour ; July 9 ; 1 6 . 



Pelican Island, Barbados ; 2 6 1 9 . Tide pool ; May 11 ; 1 5 

 2 9 ovig. 



Barbados ; 1 5 . From coral head ; June 4 ; 1 6 . Shore ; 1 9 

 ovig. Under sea anemones; 3 6 5 9 (4 ovig.) 1 juv. 



