ADESMACEA. 59 



parts of the globe, but attain the greatest size and richness of 

 colouring in tropical climates ; particularly in the West India 

 Islands. 



ACHATINELLA. Sow. A small group of shells, differing from 

 Achatina in having the inner edge of the outer lip thickened, and 

 a slight groove near the suture of the spire. Fig. 287. Sand- 

 wich Islands. 



ACHELOIS. Montf. Conilites Achelois. Knorr. Supp. T. 4, fig. 1 . 



ACICULA. Nilson. Achatina Acicula, Auct. Cionella, Jeffreys. 



ACIONA. Leach. A genus described by De Blainville as consisting 

 of those species of Scalaria, the whorls of which do not touch each 

 other. If this account be correct, the genus proposed by Leach 

 will include the typical species of Scalaria, such as S. pretiosa. 



ACME. Hartmann. A genus formed of Turbo fuscus, Walker. 

 Auricula lineata, Drap.thus described — " Shell sub-cylindrical, 

 with a blunt tip; mouth ovate, simple, thin, slightly reflected over 

 the pillar, forming a slight perforation." The animal is said to 

 resemble a Cyclostoma, but has no operculum. Auricula lineata, 

 Drap. Hist. 57, t. 3, fig. 20, 21. Southern Europe. 



ACTEON. Montf. Tornatella, Lam. 



ACTINOCAMAX. Stokes. A genus of Belemnitiform Fossils. 



ACULEATED. Beset with sharp spines, as the margin of Chiton 

 aculeatus, fig. 227. 



ACUMINATED. Terminating in a point, as the apex of Melania 

 subulata, fig. 313. 



ACUS. Humphrey. Terebra of Lamarck. 



ACUTE. Sharp, pointed, or sharp-edged. 



ADDUCTOR MUSCLE. That which draws the two valves of a 

 shell together, and leaves a mark on the inner surface of each, 

 called the Muscular Impression. 



ADELOSINA. D'Orb. A genus of microscopic Foraminifera. 



ADESMACEA. Bl. (a, without ; Acer/ioj desma, ligament.) The 

 10th family of the order Lamellibranchiata, Bl. composed of 

 Mollusca which either bore tubular dwellings in rocks, wood, &c. 

 or live in testaceous tubes, their shells being consequently desti- 

 tute of the hinge ligament. The action of opening and shutting 



