516 MR. r. G. SINCLAIR ON THE [Dec. 3, 



tubercles ; tbe ridge and Avhole tergite wrinkled and rough. The 

 ridge is not produced along the lateral margin. Posterior margin 

 straight and without a row of tubercles, but, like the anterior 

 margin, wrinkled and rough. Lateral margius somewhat rounded, 

 and coming to a blunt point nearer to the anterior than the 

 posterior margin, 



2nd tergite projects downward and forward ; point rounded. 



3rcl tergite. Lateral margin nearly straight, forming an acute 

 angle with the anterior and an obtuse with the posterior mai'gin. 



4t7i tergite more square, the anterior angle still rather obtuse. 



dth tergite. Lateral margin still forms an acute augle with the 

 anterior. The keel no longer points dowuAvard and forward, the 

 keel arises high up so that the back is little conA^ex. 



6tJi tergite. The beginning of a shoulder appears. 



7t7i tergite. A distinct shoulder ; the antero-lateral angle nearly 

 square. 



The little teeth on the posterior margin of the keel can be 

 observed in the 9th somite, but do not become conspicuous till the 

 13th. The posterior margin is never very much prolonged ; it forms 

 a short tooth but hardly a spine. The edge of the keel never 

 becomes very distinctly lobed, though a trace of lobes can be 

 observed in the posterior somites. The anterior angle of the keel 

 only differs much from a right angle in the last four somites. The 

 upper surface of the anal shield is marked with longitudinal ridges, 

 as in PL becmrii, but the arrangement is somewhat different. The 

 sub-anal region shoAvs the six tubercles along the line of the valves, 

 but only three outside the valves ; the absence of the third is 

 probably an individual variation. 



Platyrhacus insularis Humbert & Saussure, var. nov. (Plate 

 XXXL figs. 40, 41, 47, 52, 53.) 



I believe this to be a variety of the species described by these 

 authors, although it differs considerably from their description. 



Length 95 mm. Length of antennse 9^ ; distance between 

 bases of antennae 2 mm. 



mm. 

 Width of 1st tergite 9 

 2nd „ n 

 3rd „ 12 

 4th „ 13 

 5th „ 15 



mm. 

 Width of 16th tergite 14^ 

 17th „ 13 

 18th „ 11 

 19th „ 8 



Colour dark chocolate-brown, shading into lighter brown on the 

 edges of the keels. Ends of antennae rather darker than the bases. 

 The extreme edge of the anal plate light-coloured. Beneath the 

 keels, light near the edge, darker on the sides of the body ; sterna 

 and bases of legs light chocolate-colour ; ends of legs darker. 



Head covered with small smooth tubercles. Upper lip indented 

 in the middle, and furnished with a row of six bristles. Just 

 above the upper lip there is a triangular depression with three 



