AETHROPOD FAUNA OF THE WEST INDIES. 377 



Synopsis of tlie Species q/*Tityus. 



a. The inferior keels of some of the caudal seg- 



ments united androcottoides, Karsch. 



b. The inferior caudal keels not united. 



a^. A spiniform tooth beneath the aculeus of 

 the vesicle. 

 d^. Less than 50 mm. in length; flavo- 



maculate melanostictus, no\ . 



b'^. Adult over 50 mm. in length ; not 



flavo-maculate americanus (L.). 



¥. A small tubercle only beneath the aculeus 

 of the vesicle. 

 a^. Entirely fuscous, of very large size, 



23 pectinal teeth insignis, Pocock. 



b^. Flavous, variegated with fuscous, smaller. 

 a*. Caudal keels denticulate, the upper 

 edges of the 5th segment sharp 

 and carinate ; pectinal teeth 1 7- 

 a^. With 12 rows of denticles on the 

 digits of the chelae, the movable 

 digit short, the hand-back two- 

 thirds of its length obtusus, Karsch. 



5°. With 14 rows of teeth on the 

 movable digit, which is almost 

 three times the length of the 



hand-back antillanus, Thor. 



b*. Caudal keels granular, the upper 

 edges of the 5th not carinate; 

 pectinal teeth 18-22. 

 a^. Tail slender, the vesicle almost as 



wide as the 5th segment pictus, nov. 



b^. Tail robust, the vesicle much 



narrower than the 5th segment . . . Smithii, nov. 



2. TiTTUS ANDROCOTTOIDES (XarscJi). (PI. XXIX. figs. 3-3 h.) 

 Isometrus americanus, var. androcottoides, Karsch, Mitth. Munch, 

 ^nt. Ver. 1879, p. 113. 



Isometrus androcottoides, Pocock, Ann. Mag. N. Hist. (6) iv. p. 57. 



The British Museum has received very many examples of this 

 species from Trinidad (Messrs. Hart and Broadway). It is 

 common in British Gruiana {Brit. Mus., W. L. Sclater). 



