246 MONOGRAPH I A 



anterior tibia abruptly clavate ; tarsus long, conical ; ungues 

 short, the four posterior in the male with the tibiae curved, 

 the superior margin involute at the apex, having the appear- 

 ance of being twisted ; tarsi very small ; ungues long, cy- 

 lindrical, thick and curved towards the femur, so as to act 

 as a claw. Length J. 



Communicated by Francis Billam, Esq. of Newall Hall, 

 near Otley, and William Milner, Esq. of Rochdale. Al- 

 though the Guinea Pig (Cavia Cobaya), is said to be much 

 infested with this parasite, I found it extremely difficult to 

 obtain any specimens to describe. 



2. GYROPUS GRACILIS. (Louse of the Guinea Pig.) 



Plate XXIV. Fig. 2. 



Elongate, pale fulvous-yellow, finely pubescent; head and 

 thorax darker, segments of the abdomen with transverse 

 striated fascia at the sutures ; tarsi and ungues very short 

 and minute. 



Gyropus gracilis. Nitzsch. Germ. Mag. iii. p. 304. Burmeister Handbuch 

 ii. pt. ii. p. 443. Pediculus Porcelli. Sehrank. En. Inst. Aust. 500. 

 tab. i. fig. i. 



Head exserted, sub-ovate, depressed, and granulate, la- 

 brum much produced ; clypeus trilobate, marginate, tem- 

 poral margin deeply sinuated, basal lobes acute ; occiput 

 truncate ; antennae upon the anterior margin large and pro- 

 minent, the last joint very large and sub-globose ; protho- 

 rax quadrate, produced anteriorly, forming a neck, with 

 one longitudinal aud two transverse impressed lines, convex ; 

 metathorax sub-conical, with a narrow transverse fascia an- 

 teriorly, base concave ; abdomen elongate, cylindrical, finely 

 granulose, the sutural margin of each segment with a trans- 

 verse striated fascia ; apex in the male with two spinulose 

 papillae, in the female with four ; legs short and thick, ful- 



