Mr. W. Clark on the Chemnitzise. 391 



gated variety of C. acuta, which has sometimes irl'egiilar stri;© iu 

 the throat, but not near so closely set as in C. conoidea : and that 

 gentleman's C. striolata is perhaps a variety of C insculpta ; or 

 it may be a C. acuta, with the spiral striae more conspicuous than 

 usual, some of which, as we- will show below^ have- lately feecu 

 christened C. turrita. ^-Uyfu-A\ •amp.-?, nrfi Iu .ju'jjuL brio/ad .tym 



The Chem. fencstrata is very distinct, as is the elegant C. Sca^ 

 laris, which latter we have frequently, during the last thirty 

 years, taken at Exmouth, vaiying in the number of ribs, but 

 never in a living state. • 



The C. indistincta and C. clathrata are mere varieties of the 

 type C. interstincta, the animal of which is recorded in our first 

 memoir. This species, of which we have very large series, pre^ 

 sents infinite variations, in size, in the ribs, flatness and rotundity 

 of the volutions, as well as in the presence and absence of the 

 columellar tooth : these slight discrepancies have induced con- 

 chologists to constitute some unnecessary species. We have 

 examined the animal of the C. clathrata, which is a large, elon- 

 gated, toothless variety, and is so precisely similar to the one 

 described by us, that it was not thought necessary to add notes 

 on it. This species illustrates the inconvenience of a separation 

 of CJiemnitsia and Odostomia, by having the variety C. indistincta 

 deposited in the former, and the edentular variation of the type 

 in Odostomia ; and the other variety, the so-called " clathrttta," 

 is, as with us, a Chemnitzia. Surely this division of the tribe 

 will not be sustained, and all its species will merge in Chemnitzia:' 



The beautiful but common Chem. elegantissima is the staple 

 commodity amongst the shells at Exmouth, where all its vai'ie- 

 ties occur, but never alive — probably because they inhabit the 

 rocky portion of the laminarian zone, far beyond the lowest tides, 

 where the dredge cannot work ; they must be alive, in the im- 

 mediate vicinity; their numbers, and often fresh and excellent 

 condition, are sufficient proof; and we have offered what may be 

 the solution of the difficulty of obtaining them alive. ^ 



The elegant C. decussata, the " arenaria" of Montagu, abounds 

 at the same place, in the coralline zone, and with the well-known 

 C. scillce and C ucicula require no remark, as they are undis-' 

 puted species. siiio^f 



The C. clavula and C. affinis, the accredited types of whieii 

 have been placed in our hands by the favour of Mr. Barlee, and 

 have received our most attentive consideration, under evei-y mo- 

 dification of position, light, and optical aids, have fully coni 

 vinced us that they do not even offer varietal distinctions fr06S 

 the type, the Chemnitzia acicula, and we confidently predict thit 

 no animal of those varieties will ever be discovered that will ex- 

 hibit decided specialties. ■ .t 



In the notes of our first memoir we have sufiiciently men- 



