Miscellaneous. 325 



is to say, the vessels form on their journey two successive net- 

 works separated by intermediary trunks. This arrangement, a little 

 less accentuated on the floor than on the roof, added to the pre- 

 sence of a fine vibratile epithelium on the course of the pulmonary 

 vessels, proves tho active part of this apparatus as an organ of 

 haematosis. — Comptes Bendus, June 23, 1879, p. 1325. 



On the Zoantharia Malacodermata of the Shores of Marseilles. 

 By M. E. Jotjkdan. 



The anatomical plan of the Actiniadae is well known ; it may be 

 compared to a cylindrical body, furnished at one end with a buccal 

 aperture surrounded by a circlet of tentacles, and hollowed by a 

 mesenteric cavity (gastric cavity of the larva), which is connected 

 with the mouth by an oesophageal region of ectodermal origin, 

 formed by a short and wide tube. Between the oesophageal tube 

 and the walls of the body are the septa, which terminate freely by 

 the lower part of their inner margin in the mesenteric cavity. 



We have successively studied these different regions in the types 

 which presented peculiarities appreciable by the naked eye, and we 

 will here give a summary of the principal results that we have 

 obtained. 



The walls of the body contain three layers — an external cellular 

 layer or ectoderm, a fibrous mesodermic layer, and an internal cel- 

 lular layer or endoderm. 



The ectoderm is formed of glandular elements, vibratile cells, 

 epithelial elements, which are probably sensitive (analogous to 

 those of the chromatophorous sacs of Actinia equina), and, lastly, 

 neuro-muscular elements, which we have distinctly observed in the 

 above species. In Phellia this cellular layer secretes a viscous 

 mucus, which, by agglutinating fragments of all sorts, gives a 

 peculiar aspect to the body. 



In Bunodes the glandular elements of the ectodermic layer group 

 themselves together and form the little organs which adorn the 

 column of these animals. 



Cerianthus is remarkable for the structure of its mesodermic layer, 

 and thus constitutes a distinct type among the Zoantharia Malaco- 

 dermata. This layer is composed of a thick muscular region in- 

 cluded between two planes of connective tissue. The longitudinal 

 muscular fibres composing it are smooth and arranged in radiating 

 laminae. Beneath the inner fibrous plane there exists another layer 

 of circular fibres. 



In the Actinia? the mesoderm is represented by laminae of con- 

 nective tissue, clothed internally by a layer of circular muscular 

 fibres, which occur throughout the height of the column. Calliactis 

 possesses a fibrous layer of exceptional thickness and density, tra- 

 versed by persistent pores, and sprinkled in its upper part with 



Ann. & Mag. N. Hist. Ser. 5. Vol. iv. 23 



