96 Bulletin, Vanderhilt Marine Museum, Vol. II 



Mithrax (Mithrax) cornutus Saussure. 



Plate 28, fig. B. 



Name : Coral crab ; horned spider crab. 



Diagnostic characters : Known to attain a length of three to three 

 and one-half inches. Carapace elongate-ovate ; rostral horns long ; 

 four major anterolateral spines of which the first is trifid, the others, 

 each bifid; one high, postlateral spine. Basal antennal articles with 

 three spines. Orbital margin much cut, as described below. 



Type: Saussure 's type material came from the Antilles and is de- 

 posited in the Geneva Museum, 



Distribution : Florida Straits, 589 fms. ; Bermuda ; Antilles ; off 

 Havana, Cuba, 121 fms. ; between Jamaica and Haiti, 52 fms. ; Do- 

 minica, 40 to 150 fms.; Bahia, Brazil, shallow water; San Salvador, 

 "Ara" record. 



Material examined : Young specimen from Hogsty Key, San Sal- 

 vador, B. W. I., February 13, 1926, collected by the ''Ara." 



Color: Mr. Vanderbilt's notes state that this crab is deep red. 

 Saussure states that it is yellowish or rosy; often rose color. The 

 preserved specimen before me from which, when alive, Mr. Vander- 

 bilt's notes were made now answers to the Saussure description. 



Technical description: Young specimen. Carapace elongate- 

 ovate, narrower anteriorly ; 21 mm. long from base of rostrum to pos- 

 terior margin ; rostrum 9 mm. long ; maximum width 17 mm. ; upper 

 surface moderately convex, cervical and urogastric grooves deep; a 

 number of small, sharp spines on the upper surface. Rostral horns 

 slender, divergent distally, separated by a wide V-shaped space ; orbi- 

 tal margin elongate, much cleft ; preorbital tooth long, acute, directed 

 obliquely outward and slightly upward; two small acute, but well 

 separated, spines on the upper margin; the postorbital spine larger 

 than either of these but only three-fourths as long as the preorbital 

 spine; inferior orbital margin with two acute spines in addition to 

 the very long spine arising from the antennal segment. The basal 

 antennal segment has three spines in all ; a small spine at the base of 

 the first free article ; the very long spine at the external angle, which 

 is directed obliquely outward and forward and is a trifle more than 

 half as long as the rostrum; it is armed on the upper side with two 

 or three spinules ; the third antennal spine is one-third as long as the 

 big one and is situated on the orbital border. Prof. Milne Edwards 



