Mr. W. Clark on some of the Animals of the Chemnitzise. 205 



typical indistincta and the variety ' clathrata' which are inva- 

 riably without the tooth; it never exceeds 5 J- volutions. 



The type is very common in the coralline district, but the 

 tumid variety is oftener met with in shelly mud. 



Chemnitzia indistincta, Mont, et auct. 

 Chemnitzia clathrata, Brit. Moll. 



The animal inhabits a white subopake shell of six or seven, 

 sometimes eight, rounded volutions, with close-set waved longi- 

 tudinal plicse that have 3-5 rows of short lines forming a lattice- 

 work between the ribs, sometimes on them, at the bases of the 

 three or four last whorls ; the body is not near half the length 

 of the entire shell ; the aperture is always destitute of a tooth. 

 The animal in the body volution is pale yellowish subhyaline 

 white, aspersed with minute snow flakes, but the posterior volu- 

 tions are dark lead-coloui*, visible through the shell. When the 

 neck is greatly protruded, two parallel longitudinal lines are 

 seen forming an open canal, perhaps for branchial purposes. 

 The rostrum is long, rather narrow, and just rounded at the 

 termination. The tentacula are very short, united at the bases, 

 with their thin margins unfurled on the march, which gives 

 them, instead of the usual auriform figure, a very large, subtri- 

 angular, broad, leafy aspect; they terminate in large inflated 

 white tips, and are often delicately powdered with a pale, thin, 

 cloud-like sufifusion of excessively minute lemon-coloured points ; 

 the eyes are very black, distinct, and close together at the in- 

 ternal bases. The foot is large, thin, subhyaline, either trun- 

 cate or concave in front, dependent on the will of the animal, 

 with very large auricles, which in progression are used as 

 feelers ; the margins of the foot are often reflexed, as if to em- 

 brace the sides of the shell ; it is long, and when fully extended 

 reaches to the third basal volution, and ends in a needle point ; 

 sometimes on each side there is a row of small flake-white spots ; 

 it carries on a simple upper lobe, scarcely distinguishable from 

 the mass of the foot, a light corneous, thin, obliquely striated 

 pyriform operculum. 



The animal marches with rapidity, and is far more active than 

 the Ch. interstincta. It inhabits, with the variety ' clathrata,' a 

 peculiar district of shelly mud, between the laminarian and coral- 

 line zones in 10 fathoms water, off" Teignmouth. 



That this is Montagu's Turbo indistinctus is scarcely doubtful ; 

 he says that his examples have six volutions, and no fold in the 

 aperture — that is the number of the ordinary run of specimens ; 

 but both the type and variety, when very fine, have 6^ to 8 turns, 

 as our magnificent series will show. 



