The Blind Shells - Tube Shells - Family Caecidae

THE BLIND SHELLS - TUBE SHELLS - FAMILY CAECIDAE Shell minute, tubular, spiral at first, but becoming merely cylindrical, often losing the spiral part; one or more septa in posterior end of shell; foot short, bearing horny operculum; mantle thick, fleshy, circular; tentacles bear eyes; gill single. An interesting family of one genus of small mollusks inhabiting warm seas.

Genus CIECUM, Flem.

The strange development of this mollusk has been recently investigated. " In the young of Cxcum the apex is at first spiral but as growth proceeds and the long tube begins to form, a septum is produced at the base of the apex, which soon drops off. Soon afterwards, a second septum forms a little farther down, and a second piece drops off, leaving the shell in the normal cylindrical form of the adult."— Cooke.

Much confusion has been caused by conchologists who classi fied members of this genus at different stages of development in widely separate groups because they had no knowledge that such changes of form occur in the life history of the individual.

The Florida Blind Shell (C. Floridanum, Stimps.) is a curved white horn of about thirty-two narrow rounded whorls. The sinuses are wider than the rings. The posterior end is closed with a septum bearing a sharp point. The mouth is oblique.

Length, inch.

Habitat.— Cape Hatteras to Florida.

C. pulchellum,

Stimps, of an inch long, brownish, with twenty-five rings and a blunt posterior septum, comes from New Bedford, Mass., and neighbouring beaches.

This "pretty blind shell" reveals its exquisite structure under the microscope, though no larger than a grain of rice.

It does not escape the eye of the collector who is out for small 169 The Blind Shells. Tube Shells snails. A quantity of this species was uncovered in dry sand under a piece of driftwood on the beach at the extreme end of Long Island.

It is incomprehensible to some people that grown-up men can spend time searching for shells so small they are scarcely visible to the unaided eye. "Too small to putter with," is the ultimatum. Such people cannot understand the fact that to the mind that grasps the limits of the great animal group, Mollusca, no family, however small in size or scope, is insignificant. In fact, each species and variety is big with meaning. It is only small people who fail to grasp this fact. Only the ignorant can think the naturalist, in the field or the laboratory, is wasting time.

C. crebricinctum,

Cpr., is red-brown, with dark streaks running lengthwise across the eight close rings. The tip is pointed. Length, a inch.

Habitat.— Southern California.

C. Californicum, Dalt, is a narrow curved shell with very fine rings. Length, scarcely inch.

Habitat.— San Diego, Cal.

C. Cooperi,

Smith, I inch long, is cross ridged, which gives it considerable beauty under a lens. It is found in New England and off Long Island.

C. nitidum, Stmps.,

is a very swollen form contracted at both ends; the shell is shiny and pale brown. Length, inch. Habitat.— Florida.

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