384 MR. E. I. POCOCK ON THE 



length of the two females is due to the fact that the trunk of tlie 

 female of T. pictus is very much shrunken. The largest female 

 of T. Smithii measures 63 mm. in length, the carapace being 6-5. 



The pectinal teeth are the same as in T. pictus, varying from 

 18-21 in the female, and from 20-21 in the male. 



Of this species I have seen three males and three females from 

 Grenada, collected by E. V. Sherring, Esq. ; and two males and 

 two females from the Grenadines (Mustique and Bequia) 

 obtained by H. H. Smith, Esq. 



The examples from Mustique and Bequia differ from the others 

 in having the tooth beneath the aculeus noticeably smaller, being 

 merely a minute tubercle scarcely observable by the naked eye. 

 Another difference, to which, however, analogy forbids one to 

 attach much importance, is the greater width of the hand. 

 Thus in a specimen from Grenada having the hrachiiim 2'5 mm. in 

 width, which is the same as in the male from Mustique Island, 

 the manus is only just over 8 mm., while in the male from 

 Mustique Island the manus is 4 mm. Curiously enough, too, 

 in both the specimens from Mustique Island the movable digit 

 has its distal third ferruginous, while in the Grenada form the 

 digit is ferruginous only at the apex. 



Since these characters also obtain in the specimens from 

 Bequia, I propose to regard these Grenadine examples as repre- 

 sentatives of a variety which may be called microdon. 



9. *TlTTUS ANTILLAKUS {TllOrelJ). 



Isometrus antillanus, Thorell, Etudes Scorpiol. pp. 60-62. 



This species, described from a single female example from the 

 Antilles, is unknown to me. 



Prof. Kraepelin suggested that it might be one of the synonyms 

 of T. americanus. It is, however, not T. americanus as recognized 

 by me. 



In colouring it approaches T. ohtusus, T. pictus, and T. SmitJiii, 

 being testaceous and marbled with black ; it differs from them all, 

 how^ever, in having the vesicle flavous. 



The carapace is subtly granular, but more coarsely anteriorly ; 

 the tergites, too, are subtly granular ; the sternites are very subtly 

 coriaceous. 



Tail very nearly six times the length of the carapace, parallel- 

 sided, the width of the first segment and fifth being equal ; 

 the keels are denticulate, and the superior lateral keels of the 

 fifth are acute and bluntly denticulate 3 the intercarinal spaces 



