114 Rev. T. A. Marshall's monograph of 



cubital avcolet not separated from the praediscoidal ; pobracliial 

 shorter than the praebrachial ; recurrent nervure interstitial. 

 Terebi'a cuncealed or subexserted. 



The species are of stout subcylindrical form, with 

 hard integuments, covered with rugosity irregularly dis- 

 posed in strife or reticulated, and mixed with coarse 

 punctures. They are black, frequently with a pair of 

 testaceous spots, round or triangular, occupying the 

 region of the spiracles of the 1st abdominal segment, 

 and sometimes confluent. In C. Wcsmaelii, Cur., the 

 abdomen is broadly rufous above. The legs are rufo- 

 testaceous, usually diversified with black. C. ^ndlaius, 

 Dahlb. (Sv. Ak. HandL, 1838, p. 163) is described as 

 wanting the 2d cubital areolet, and seems therefore to 

 belong to some other genus. 



The abdomen, viewed from above, generally shows no 

 vestige of sutures ; but one or two are sometimes indi- 

 cated by slight transverse depressions. On the under 

 side it has the appearance of being eviscerated ; the 

 refiexed edges surround an oblong cavity, against the 

 walls of winch the belly is flattened after death by 

 shrinking. The sutures of the ventral surface are 

 always more or less visible ; in the male at least five 

 segments may be counted, showing that the shield is 

 compounded of more than the first three segments. 

 The sexual distinctions are best seen on the under side ; 

 the terebra originates just behind the middle of the 

 abdomen, and is either falcate or straight ; in the former 

 case it curves upwards in a reverse direction to the con- 

 tour of the abdomen. The valvula ventralis is distinct, 

 contained within the shell in repose, but cajmble of being 

 moved downwards and l)ackwards so as to allow the 

 terebra to pass the reflexed apical edge, in which a 

 shallow groove is often cut for its reception. Many of 

 the males exhibit a variously-shaped fissure at the apex 

 of the abdomen, in the centre of which may be discerned 

 the sheath of the generative organ, sometimes mistaken 

 for the terebra, and the cause of confusion of sexes in 

 the descrijitions. In most cases the antennaj are also a 

 guide to the determination of the sexes ; those of the 

 male are longer, setaceous, or tapering gradually to the 

 extremity, while in the female they are shorter, com- 

 presso-dilated beyond the middle, and thence somewhat 

 aljruptly diminishing to the apex. The absence of a 

 valvula ventralis will also serve to distinguish the males. 



