G8 Miscellaneous. 



of concentrif lines of the surfuoe of the soaU^ tliere is a region of 

 peiuliar ajipoaiance. which M. Agassiz (U'signates the " centre of 

 growth," and ^landl the " focus," by wliich he understands " focus 

 of nutrition." M. Agassi/, regards this regit)n as the oldest portion 

 of the scale, the layei-s of which have been worn away. As regards 

 the first point, that of age, he is undoubtedly right ; as regards the 

 second, this is not the case. If the asperities are less prominent in 

 this part of the scale, it is because they date from a period when 

 the hsh was smaller. — Anhiv fur Anat. Phys. uml tvi.ss. Meilizin, 

 1808, p. 729 ; Blbl. U>dv. November 15, 18G9 : Bull Scl. pp. 276- 

 278. 



On the Anatomy of the Alcyonaria. 

 13y MM. G. PoLCUET and A. Myevre. 



The anatomical systems of most of the inferior animals have not 

 even yet been clearh" determined. The existence of distinct miis- 

 cular elements in particular, long admitted upon the testimony of 

 the movements which one sees executed by the animals, has only 

 been demonstrated quite recently in the Act'inice by M. Schwalbe. As 

 to the Alcyonaria, M. C. Genth has indeed described the muscles of 

 Solenogonjia tulndosa ; but his description is very incomplete, and 

 even it does not stand in any relation to what we have been able 

 to make out of the muscles of two other Alcyonaria, Alcyonium 

 diyitatum and A. jinhnatum. 



The muscular elements are pale fibres, soft during life, about 0*002 

 millim. in diameter when they are at the maximum of contraction, 

 but usually much more slender. They are finely granular, without 

 nuclei, and have distinct outlines. They may easily be isolated, at 

 least in part of their length, which is variable. These muscular 

 fibres are, by their appearance and size, very like those of the 

 Nemertea. These fibres, in the Alcj^onaria, are arranged sometimes 

 in sheets, and sometimes in thicker or thinner bundles, which form 

 true muscles, having sometimes very definite insertions, and needing 

 to be described and named as so many primarj' organs. 



1st, Lonfjitud'mcd Muscles. — They are eight in number, and corre- 

 spond to each of the mesenteroid lamina;, which they themselves 

 assist to form. They extend from the peristome far into the cocnen- 

 chyma {sarcosome of M. Lacaze-Duthiers), which we find still 

 very distinct upon the walls of the wide canal, which forms a con- 

 tinuation of the bodies of the polypes {grossere Saft-KanaJe of 

 Kolliker). 



2nd. This canal i)resents throughout, beneath the epithelium 

 whicli lines it, a layer of circular or transverse fibres, covering and 

 crossing at right angles the fibres of the longitudinal muscles lying 

 against the substance of the ccenenchyma. These fibres, retaining 

 their direction, give form to the mesenteroid laminae ; and they 

 are to be found still, under the same conditions, even on the wall 

 of the perigastric cavities. 



3rd. Sphincter. — This muscle occupies the peristome. It is formed 



