228 Dll. T. DAVIDSON ON EECENT BEACHIOPODA. 



Uncertain Species. 

 129. Glottidia (?) ANTiLLARTJM, Eeeve, sp. (Plate XXVIII. fig. 13.) 



Lingula antillarum, L. Eeeve, CoBch. Icon., Monogr. oi Lingula, pi. ii. fig. 8, 1861. 

 ? Glottidia antiUamm, Dall, Proc. Acad. Nat. Sci. Philadelphia, p. 204, 1873. 



Shell elongated ovate, broadest posteriorly, tapering at the beak, pinched in anteriorly 

 at the sides, and almost straight in front. Valves very slightly convex and flattened ; 

 surface smooth, marked only by concentric lines of growth, light yellowish anteriorly, 

 tinged with blue-green towards the umbones. Length of shell 8, breadth 3^ lines. 

 Length of the peduncle not known. 



Hah. Martinique, dredged at a depth of sixteen fathoms (Cuming). 



Obs. This is a very uncertain species, and may be a young specimen of some other form. 

 Mr. L. Reeve states that he has seen only one specimen, which appears distinct, and whose 



permeates the mantle-leaflets. But Dr. Be3-er considers these fibres as nothing more nor less than supporting fibres, 

 "passing in various directions, but having for their purpose the fixation of the cavities through which thcj- extend." 



The peritoneal ejnthelium " consists of flattened polygonal cells, with small, round, central nuclei ; these cells are 

 joined together edgewise, and form a very thin and delicate membrane, which lines the walls of the perivisceral 

 chamber, the mantle sinuses, and blood-laeunes, covers all the viscera and mesenteric bands, and gives rise to blood- 

 vasoular spaces and channels within the body-cavity." 



" All the muscles in Lingula are composed of long parallel fibres, and belong to the variety of smooth muscle- 

 fibres." The structures described by Hancock as ' parietal muscles,' and by Gratiolet as ' muscles haussieres,' as 

 well as the muscles on the arms and the peduncle, Beyer regards not as muscles, but rather " as a mesenchymatoua 

 supporting substance possessing a certain amount of elasticity, but lacking the contractibiUty proper to muscular 

 tissue only." 



He was unable to detect any central propelling organ of the vascular system, and confirms the views held by 

 Shipley, Shulgin, Semper, and Morse as to the absence of a heart. He detected the presence of three diflerent kinds of 

 corpuscles floating in the circulating fluid, in addition to those connected with the structure of the shell ; the 

 blood-corpuscles proper, small round granular corpuscles, recurring chiefly within the mantle-sinuses and their 

 branches. These he was led to regard " as young ova which sooner or later become transformed into fuUy developed 

 ones," and peculiar, spindle-shaped, or oblong ovoid, striated bodies called spermatophorcs by Hancock, and young 

 Lingido! by Gratiolet. 



Dr. Beyer divides the digestive apparatus of Lhvjida into three parts, viz., " The mouth and oesophagus, the 

 stomach and livcr-lobulcs, and the intestinal canal proper. . . . The apparent great strength of the tissues surrounding 

 the mouth and the prominences in the wall itself seem to imply a certain power for grinding the most solid food- 

 particles before they pass on into the oesophagus through a valve-like structure permeated with supporting fibres. . . . 

 The opening of the anus seems to be valve-like, running for a short distance within the supporting layer of the body- 

 wall before opening to the exterior." 



The author adheres to the number and division of tlie nervous ganglia as given by Hancock in Waldhcimia 

 austndis. " There are in Linr/uJa,'' he says (p. 250), " five distinct nervous ganglia connected with the circum- 

 cesophageal commissure. . . . The great central suboesophageal, the two ventro-lateral, and the two dorso-latcral or 

 8upra-oesophageal ganglia" (the smallest of all). 



" The description of the genital apparatus of ZjXf/j(fo may be divided into two parts, namely: — 1. That of the 

 genital glands, the organs producing the ova and spermatozoa respectively ; and 2. That of the oviducts or segmental 

 organs (Morse), which conduct (he spermatozoa and ova into the pallial chamber, and thence into the sea-water. . . . 

 The description of the generative glands in Wcddheimia austrcdis, a Testicardine Brachiopod given by Hancoclc, is in 



