ZOOLOaY AND BOTANY, MICROSCOPY, ETC, 59 



into a terminally dilated tongue ; larger glandular cells also occur 

 here, and small scattered epithelio-muscular ones. The longitudinal 

 muscles are composed of extremely long fibres, which, owing to their 

 possession of numerous nucleated prominences on one side, must be 

 regarded as compound, and as such are termed pluricellular ; they are 

 also found in the mesenteries of Phellia. Nervous elements are recog- 

 nized in certain fine nucleated fibrils ; they form a difluse plexus at 

 the base of the ectoderm, connecting the epithelial with the muscular 

 elements, and must be regarded as putting these two sets of cells in 

 communication ; they resemble those found by Claus in the Medusa 

 Charybdea. The cesophagiis dififers from the body-walls by the pos- 

 session of glandular cells. 



Body-walls. — The peculiar firmness of the column is due to the 

 mesoderm, which, in section, resembles hyaline cartilage. The ecto- 

 derm consists solely of fusiform cells, without cilia, closely pressed 

 together ; they end externally in conical points. The mesoderm 

 consists mainly of fibrous tissue, less dense the nearer it is to the 

 summit of the column ; the fibres have a vertical direction ; there are 

 two layers, the internal of which is regularly laminated, the outer not 

 so; at the upper part of the column circular muscular fibres appear 

 in this fibrous tissue, and increase in number, till at the summit they 

 constitute its entire thickness. Longitudinal muscles occur as usual 

 on the internal aspect of the mesoderm. The development of muscles 

 within the mesoderm to this extent separates the genus distinctly from 

 other genera, and explains the energy of the contractions of the body. 

 The basal pores for emitting the mesenteric filaments are the outer 

 ends of simple tubes, provided with a cellular lining but no special 

 muscles. 



The foot-dish secretes a viscous mucus, which aids in fixing the 

 animal. Mesenteries. — Several orders are recognized, a fact interesting 

 with regard to the connection between the soft and stony Zoantharia. 

 There are two kinds of filaments ; those with cilia are never emitted 

 by the pores, the others consist of an external layer of thread-cells, a 

 subjacent granular layer, and a fibrous axis which connects them with 

 the mesentery, and is readily severed by contraction. 



The chief point worthy of notice in Adamsia palliata is the large 

 size of the male glands. 



Phellia elongata. — The ectoderm of the tentacles has, beside glan- 

 dular cells and nematocysts, a variety of epithelial forms, some pos- 

 sessing basal filaments, which differ, however, from those of epithelio- 

 muscular cells, and resemble those in the Medusae called nervous by 

 the Hertwigs. The ridges of the body-walls are formed of ectoderm 

 and mesoderm ; the former is very thin and marked by a coat of 

 mucous matter containing foreign materials, and consists of the same 

 elements as the tentacles, substituting true muscular cells for those of 

 possibly nervous origin. The mesenteries are remarkable only by the 

 great development of the muscles, which form a large longitudinal band 

 along one side of each mesentery ; they have generally the peculiar 

 characters of the tentacular muscles of Calliactis ; they also exhibit 

 waves of contraction. The reproductive organs lie at the bottom of 



