DE. T. DAVIDSON OX EECEXT BEACHIOPODA, 27 



Ml". Uall, iu bis paper in the Bull. Mus. Coiup. Zool. already referred to, enters into 

 many details to show that it is a distinct species. He has since then written me that, 

 although T. Cailleti may be a southern form of T. cajnit-serpentis, be has seen 

 probably nineteen twentieths of all the existing specimens, and that it seems to him to 

 be as well disting-uisbable as any of the fossil forms, and that he considers it at any rate 

 fully entitled to a varietal name, as it is well distinguished by its granulated ribs, and 

 varies much in form. 



Dall says {I. c. p. 10) " That the smallest specimens of tliis species which I was able 

 to find among those sent by M. de Pourtales were nearly -1 inch in length. That 



the characteristic sculpture was developed upon them to the very apex of the shell 



The various muscles were already well developed. The mouth was as described in the 

 young of the T. cubensis. The intestine was short, cylindrical, and straight. The loAver 

 portion was embraced by a few hepatic digitations. These lobes were very dark brown, 

 the muscles of a deep reddish brown, and the brachia of a flesh-colour. The latter were in 

 the shape of a horseshoe, with no trace of a median lobe. They were close set and marked 

 with transverse lines as in T. cubensis. The membrane which covered the viscera was 

 covered internally with irregular hyaline spots with well-marked bou^ndaries, which no 

 doubt are the limits of the lacunar channels of circulation. The mantle was quite trans- 

 parent, with a brownish edge, and in each of the internal channels, corresponding to the 

 ribs of the outside of the shell, was a single bristle, composed of longitudinal fibres of 

 chitine, without any of the transverse markings which are seen in the setae of the adult. 

 The extreme tip of the bristle alone protruded from the mantle, and its inner extremity 

 was slightly bulbous. It was of a glistening yellow color throughout. In those adults 

 which I examined there Avere only five or six of these setse iu each mantle lobe. These 

 specimens were obtained off Havana, in two hundred and seventy fathoms water. The 

 very extraordinary manner in which all the soft parts were crowded and crammed with 

 masses of calcareous spiculse defied my best efforts to obtain any very satisfactory results 

 from the two or three alcoholic specimens at my command. A flocculcnt mass of white 

 matter resisted the action of acid, and filled all the interstices of the membranes so as to 



render them quite opaque The intestine was cylindrical, and ended much as it does 



in T. cajnit-serjjends. The mouth was surrounded by a dark-brown line. There were no 

 structures above and behind the mouth, such as are described as existing in T. cubensis. 

 The attached extremities of the muscles were of a very bright red-brown. . . . The peduncle 

 is white, slender, and exceedingly long, the exposed portion sometimes equalling in length 

 one third of the shell. A brownish tinge pervaded all the tissues of the adult. Transverse 

 markings were noticed iu the brachia, as described in other species by Hancock. One 

 specimen, growing on a rock which had become covered with sponge, afforded an interesting 

 observation. The peduncle was exceedingly long, and on cleaning off the sponge it was 

 seen that the creature, on the growth of the sponge towards it, had apparently lengthened 

 its peduncle to get out of the way ; and while the original attachment still remained, . . 

 . . somewhat further on, nearer the shell, a second attachment of the peduncle had taken 

 place by the outgrowth, from the underside, of a biincli of cylindrical rootlets, exactly 



resembling the attachment of an ivv to a stone. 



4* 



