DESCRIPTION OF PLATES, 21, 22. 655 



Fig. 1 d, Verruca Stromia, smooth var., reversed specimen, i. e., with 

 the right hand scutum and tergum fixed and modified into 

 part of the shell. 



1 e, Verruca Stromia, shell seen from the under side ; the right 

 hand scutum and tergum (as in I d) being the fixed pair : 

 the moveable scutum and tergum (s, t) are seen in the 

 shade at the bottom of the shell, and their shape will be 

 best understood by looking at fig. If. The fixed scutum 

 and tergum s', t', differ a little in shape, and w the form 

 of their line of junction, from the same two valves (re- 

 versed) in fig. 1 c. 



1 /, Verruca Stromia, moveable scutum and tergum, seen from the 

 under side, taken from a specimen, in which (as in 

 1 d and e) the right hand scutum and tergum were the 

 fixed pair. 



2, Verruca Spengleri, scutum seen from the under side, 

 showing the medial, prominent adductor ridge ; taken 

 from a specimen, in which the right hand scutum and 

 tergum were fixed. 



3 a, Verruca laevigata, scutum and tergum, external view of, from 

 a specimen in which the left hand pair was fixed ; 3 b, 

 scutum and tergum, internal view of, from a specimen, in 

 which the right hand pair was fixed. 



4, Verruca prisca, scutum and tergum, external view of, from a 



specimen, in which left hand pair was fixed. 



5, Verruca nexa, with the valves separated, the left hand scutum 



and tergum being the fixed and modified pair. 



6, Portion of ribbed shell of a Venus, to which a Verruca 



Spengleri had been attached, showing the peculiar form of 

 the excavation. 



PLATE 22. 



ALCIPPE LA.MPAS. 



Fig. 1, Entire animal (female and two males) greatly magnified, being 

 an unusually symmetrical specimen, partly copied from Mr. 

 Hancock's Plate (' Annal. and Mag. Nat. Hist.' ser. 2, vol. 

 4, PI. VIII). h, horny disc and surface of attachment; 

 a, projection formed by the lower end of the lip of the orifice 

 leading into the sack ; m, a pair of males, of their proper 

 proportional sizes, attached in their ordinary position. 



2, Entire animal, much distorted. 



3, Small portion of a Fusus (copied from Mr. Hancock's Plate), 



perforated by the Alcippe ; the darker curved marks are 

 the slit-like orifices, leading into the chambers; the latter 

 are seen from the outside, owing to a difference of tint in 

 the shell of the mollusc where worn thin over the chambers ; 

 they are represented by the fan-shaped shaded patches. 



4, One of the orifices, leading into a chamber, much enlarged ; 



«, the curved narrow end, which was open and used 



