ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 781 



the muscles in Lingula belong to the smooth variety, none are striated 

 as in the Testicardinates. The " parietal muscle " of Hancock, as well 

 as the " muscle " in the arms and peduncle, are not muscular, but 

 " mesenchymatous supporting substance, possessing perhaps a certain 

 amount of elasticity, but lacking contractility." 



As to the vascular system, the author agrees with Shipley, Schulgin, 

 and Morse, that the older writers were wrong in their description of 

 a " heart " : no such pulsating organ can be found in Lingula. Four 

 different kinds of corpuscles are found in the fluid of the coelom and 

 its connections: (a) small round granular corpuscles, regarded as 

 young ova ; (b) spindle-shaped, striated spermatophores ; (c) the cor- 

 puscles found below the cuticle of the shell and elsewhere ; (d) blood- 

 corpuscles proper, which are round bodies, with homogeneous proto- 

 plasm and a small nucleus. The alimentary canal is lined by a 

 ciliated epithelium surrounded by a thick layer of very small cells, 

 in which, near the circuni-cesophageal uerve commissure are large 

 apolar ganglion-cells ; outside this layer is a layer of supporting 

 tissue. From the stomach several regularly arranged branching ca3ca 

 are given off: these are " liver lobules " ; the wall of each consists of 

 a thin layer of supporting substance with peritoneal epithelium, 

 within which is a single layer or several layers of rounded granulated 

 nucleated cells surrounding a lumen. 



The nervous system agrees with that of Waldheimia as described 

 by Hancock, rather than with the descriptions by other authors, which 

 Dr. Beyer quotes. There are five ganglia round the oesophagus : a 

 " great central subcesophageal ganglion " ; two " ventro-lateral " ; and 

 two " supra-cesophageal ganglia : these last are smaller than the 

 others. The two ventro-lateral ganglia are connected with one another 

 by a commissure ; each is also connected with the subcesophageal 

 ganglion, and to the supra-cesophageal ganglion of its side. This 

 last commissure forms the circum-cesophageal commissure, which 

 gives off pallial nerves, and passes along the base of the arms, 

 which are themselves supplied by nerves from the supra-cesophageal 

 ganglia. The author is not certain as to the existence of certain 

 " sensory cells " in the ectoderm described by Schulgin. 



The genital apparatus consists of the genital glands and the 

 " segmental organs " or genital ducts ; these are the structures which 

 were, by the older writers, regarded as " hearts." While the majority 

 of authors, both ancient and recent, have regarded Brachiopods as 

 dioecious, the present author feels no doubt that Lingula is herma- 

 phrodite, as he found both ova and spermatozoa in the same animal, 

 though both elements were not equally developed at the same time. 

 The genital glands occur in the mantle, and the arrangement of the 

 ovary is nearly the same as that in Waldheimia, as described by 

 Hancock ; the genital elements are derived from the ccelomic epi- 

 thelium, and are seen in the meshes of the supporting substance of 

 the mantle ; but in the visceral chamber the ovaries are confined to 

 the mesenteric bands, while the spermatozoa occupy the peripheral 

 walls of the cavity. The " segmental organ " or " oviduct " has 

 been accurately described by previous writers. It appears to function 



