The great _Glandina_, which attain their maximum development in Mexico and the southern United States, are a very noticeable family in this group. According to Mr. Binney,[124] _Glandina truncata_ Gmel., one of the commonest species of the genus, is somewhat aquatic in its habits. It is found in the sea islands of Georgia and around the keys and everglades of Florida, where it attains a maximum length of 4 inches, while in less humid situations it scarcely measures more than 1 inch. It occurs most abundantly in the centre of clumps and tussocks of coarse grass in marshes close to the sea-coast. By the action of the sharp, sickle-shaped teeth of its radula the soft parts of its prey (which consists chiefly of living Helices) are rapidly rasped away; sometimes they are swallowed whole. It has been known to attack _Limax_ when confined in the same box, rasping off large pieces of the integument. In one case an individual was noticed to devour one of its own species, thrusting its long neck into the interior of the shell, and removing all the viscera. [Illustration: FIG. 21.--_Glandina sowerbyana_ Pfr. (Strebel).] The _Glandinae_ of southern Europe, although scarcely rivalling those of Central America in size or beauty, possess similar carnivorous propensities. _Glandina Poireti_ has been observed,[125] on Veglia Island, attacking a living _Cyclostoma elegans_. By its powerful teeth it filed through two or three whorls of the shell of its victim, and then proceeded to devour it, exactly in the same manner as a _Natica_ or _Buccinum_ perforates the shell of a _Tellina_ or _Mactra_ in order to get at its contents. Few observations appear to have been made on the habits or food of _Streptaxis_, _Rhytida_, _Ennea_, _Daudebardia_, _Paryphanta_, and other carnivorous Mollusca. A specimen of _Ennea sulcata_, enclosed in the same box as a Madagascar _Helix_ (_sepulchralis_ Fér.) many times its own size, completely emptied the shell of its inhabitant.[126] Mr. E. L. Layard informs me that certain Cape _Rhytida_, _e.g._ _R. capsula_ Bens., _R. dumeticola_ Bens., and _R. vernicosa_ Kr., eat _Cyclostoma affine_, _Helix capensis_, _H. cotyledonis_, etc. To Mr. Layard I am also indebted for the--perhaps apocryphal--tradition that the best time to capture the great _Aerope caffra_ Fér. in numbers was after an engagement between the Kaffirs and Zulus, when they might be observed streaming from all points of the compass towards the field of slaughter. The Cuban _Oleacina_ are known to secrete a very bitter fluid which they emit; this perhaps produces a poisoning or benumbing effect upon their victims when seized. They devour operculates, _e.g._ _Helicina regina_ and _sagraiana_.[127] CHAPTER III ENEMIES OF THE MOLLUSCA--MEANS OF DEFENCE--MIMICRY AND PROTECTIVE COLORATION--PARASITIC MOLLUSCA--COMMENSALISM--VARIATION =Enemies of the Mollusca=