162 Bibliographical Notices. 



Soon after the last -mentioned date MM. Carriere and Theodore 

 Barrois undertook independently elaborate reseaches for the purpose 

 of settling the question, and the description of the investigations of 

 the latter zoologist forms the first part of the volume before us. M. 

 Barrels has examined over sixty species of bivalve Mollusca belong- 

 ing to the most various gronps, and the result of his investigation 

 has been to convince him that the byssus is certainly a secreted 

 organ, and that traces of it are to be found in nearly all the families 

 of the Lamellibranchiata. In its most complete condition it consists 

 of — 1, the byssus itself; 2, the groove with its glands ; 3, the canal 

 of the byssus ; 4, the cavity of the byssus vpith its glands. Of 

 these the last is apparently the most important part, as it is there 

 that the materials of the byssus are secreted, and in those forms in 

 which the byssus is highly developed this cavity is divided by a 

 multitude of vertical lamellae into a number of secondary cavities, 

 each of which gives origin to one of the roots of the byssus. The 

 glands which lino this cavity are of two kinds, some continuous 

 with the glands of the groove, and the others of much smaller 

 dimensions, which generally occur only in those forms which have the 

 byssus highly developed. The author seems to be inclined to con- 

 sider the latter oidy a modification of the glands of the groove, which 

 of themselves seem to suffice for the production of a true byssus. 



Upon all these points and many others M. Barrels furnishes us 

 with very full information, and his work ought finally to set at rest 

 the question of the true nature of the byssus. 



The second section of his book treats of a subject, the importance 

 of which was forced iipon him during his investigation of the glands 

 of the foot in the bivalve Mollusca, namely, " the introduction of 

 water into the circulatory system of the Lamellibranchiata through 

 the so-called pori aquiferi.^' This is a subject upon which a greater 

 variety of opinion has prevailed than even with regard to the origin 

 and nature of the byssns, and the analysis of the literature relating 

 to it given here by M. Barrels shows to how great an extent it has 

 attracted the attention of naturalists. The author agrees with those 

 who maintain that there is no intermixture of water with the blood 

 of the Mollusca ; he denies the existence of the intercellular passages 

 destined to facilitate this intermixture, described by several writers, 

 and declares the supposed j/'Ori aqniferioi other naturalists to be the 

 apertures of the byssogenous apparatus, having no communication 

 with the lacunar system of the foot. The organ of Bojanus he con- 

 siders to be already put out of court by the researches of many 

 naturalists, and hence he concludes that there is no direct commu- 

 nication between the exterior and the circulatory system, and that 

 the blood is never mixed with water. The turgescence of the foot, 

 which was supposed to be due to the influx of water into the circu- 

 latory lacunae, he regards, with Fleischmann and Bay Laiikester, as 

 caused by the sudden transfer of blood from the great reservoirs of 

 the mantle to the spongy tissue of the foot. 



We have given here only a very imperfect notion of the contents 

 of this volume, which gives the detailed results of some admirable 

 work upon two matters of considerable importance in the natural 



