Report on Zoology. 



137 



Prof. Morse maintains that the group of animals called 

 brachiopods are not mollusks, as heretofore supposed, but 

 that they more properly belong to the sub-kingdom artU 

 culata; that their affinities are with the crustaceans and 

 annelids, and most closely allied to the tubiculous worms 

 (worms forming shelly tubes for the protection of their 

 bodies). By the study of the embryology of the terebra- 

 tulina and living forms of decina and lingula, he has amassed 

 an amount of evidence in favor of his statement that has 

 not only convinced himself but many other naturalists that 

 the brachiopods are improperly placed among the mollusks, 

 and their affinities are as above stated. The shells of the de- 

 cina and lingula are similar, he says, to that of the Crusta- 

 cea both in their tubular structure and their chemical 

 composition. In lingula, while the carbonate of lime is 

 only six per cent, the phosphate of lime amounts to forty- 

 two per cent; the shells of Crustacea are also composed 

 mainly phosphate of lime. 



The horny setae which fringe the mantle of brachiopods 

 are secreted by follicles, and are surrounded by muscular 

 fibres, so as to be freely moved by the animal, and are 

 remarkably worm-like, differing but little from those of 

 worms when they are enclosed in muscular sheaths, while 

 in other articulate animals they are simply tubular pro- 

 longations of the epidermal layer. 



The pedicle of lingula, Prof. Morse says, is hollow, and 

 composed of three distinct layers, and is distinctly and reg- 

 ularly ringed orannulated, presenting a remarkably worm- 

 like appearance. It has layers of circular and longitudinal 

 fibres, and is contractile, or capable of being coiled or un- 

 wound at fall length. The formation of a sand tube as a 

 protection to the peduncle is also referred to as a strong an- 

 nelid character. This tube is formed by a secretion from 

 the pedicle which cements the particles of sand, and if this 



Trans. vii.~\ 18 



