380 LO WER FORMS OF MARINE LIFE 



heedless of danger. When opening oysters and clams, these American whelks 

 frequently fracture or crush their own shells, a circumstance which accounts for 

 their frequent irregularity of growth. 



Very conspicuous and striking, on account of their scarlet or crimson quad- 

 rangular blotches on a pure white ground (when the epidermis, or outer skin, is 

 removed), are the elongated, spiral, long-mouthed mitre-shells of the family Mitridce, 

 among which the species known as Mitra papalis is the largest and perhaps the hand- 

 somest. In this species, which is a native of the Indian seas, the shell is about five 

 inches in length, and marked with irregular red blotches arranged in diagonal lines. 



Very handsome are the capacious shells of some of the volute family (Volutidas), 

 half the members of which are Australian, while the remainder are distributed 

 over a wide area, including the seas of the West Indies, Chile, Cape Horn, West 

 Africa, and Java. The largest of all are the boat-shells (Cymba) and melon-shells 

 (Gymbium), which are generally yellow in colour, and have smooth surfaces and short 

 spires — which may carry rings of spines — and enormous apertures. The members 

 of these genera are remarkable for producing their young alive, the eggs being 

 hatched within the bodies of the parents, upon which the young are carried for 

 some time after birth. The West Indian bat- volute (Voluta vespertilio), which 

 represents the typical genus of the family, is smaller, and has the shell ornamented 

 with dark zigzag markings. 



The beautifully polished olive-shells typify yet another family of allied 

 gastropods, the Olividce, the members of which are for the most part tropical in 

 distribution ; one of the commonest, and at the same time one of the most richly 

 coloured, being the painted olive (Oliva ispidula) of the Indian Ocean. The harps 

 {Harpidce), of which Harpa ventricosa is the typical species, form a family by 

 themselves, and, unlike the olives, are characterised by the short-spired, wide- 

 mouthed, and highly polished shells carrying a number of bold longitudinal ridges. 

 The foot is large with deep lateral fissures ; and its hind part is stated to be thrown 

 off when the animal is disturbed or irritated, much in the same way as a lizard 

 discards its tail. The shell of H. ventricosa has crescent-shaped white spots on a 

 pale lilac ground bordered with brown. Belonging to another section are the 

 cone-shells (Collides), many of which are amongst the handsomest of univalves. 

 The family is widely spread over the warmer seas ; and the shells are conical or 

 fusiform in shape with long narrow mouths and very short spires. One of the 

 most exquisite is the admiral cone (Conus amiralis) of the Pacific and Indian 

 Oceans, which measures about two inches in length and is marked with white 

 triangular spots forming a delicate network on a citron-brown ground. The 

 so-called orange admiral is, however, the most beautiful of all the group ; while 

 among other lovely species are C. omaicus, C. victor, and, most valuable of all, 

 C. gloria-mar is. 



To an entirely different group belong the ormers or ear-shells, Haliotidce, 

 characterised by their rough exterior and beautifully iridescent nacreous inner 

 surfaces. These, too, attain their maximum of size and beauty in tropical seas ; 

 Haliotis splendens being one of the finest among the seventy species. Near the 

 outer edge of the shell may be observed a row of perforations through which 

 tentacular processes are protruded in the living state ; the presence of these allying 



