168 Miscellanies. 



At what age it is formed in our yonng Naiades, I am unable 

 to decide. I have discovered it to exist in many instances when 

 they had not yet formed the first concentric Une of growth on 

 their shells, and therefore conclude that they attach themselves 

 to some fixture, soon after they are ejected from the oviduct of 

 the mother. 



It is probably continued, unless accidentally destroyed, until the 

 animal attains strength sufficient to retain its position by grap- 

 pling the sand and pebbles with its extended and curved foot. 



The length of this byssus when unextended, is from four to six 

 inches ; the size that of the finest sewing silk, and the strength- 

 is so great that it will resist the force of the strongest current of 

 water, even after the animal is raised out of its bed. 



The species we found thus attached in this locality, were prin- 

 cipally the U. zigzag, elegans, dehiscens, ebenus, crassus, folia- 

 tus, pyramidatus, crassidens and gibbosus. 1 believe, however, 

 that every species has the power of forming a byssus when oc- 

 casion requires it. 



Cleveland, March 10, 1840. 



MISCELLANIES. 



DOMESTIC AND FOREIGN. 



Bibliographical Notices. — Brief notices of recent Botanical 

 works, especially those most interesting to the student of North 

 American Botany. [Communicated.] 



1. DeCandolle, Prodromvs Syste7natis Naturalis Regni Vegetahi- 

 lis, iSfC, Pars Ima. Sectio posterior. {Paris, 1839). — The second 

 part of the 7th volume of DeCandolle's Prodromus — with which our 

 notices may appropriately commence — was published at the very 

 close of the last year, and comprises the following orders, viz. Sty- 

 lidecB, LobeliacecB, CampanvlacecB, Cyphiacece, (a very small order, 

 founded on the Cape genus Cyphia, and here first proposed by Alph. 

 DeCandolle,) GoodenoviecB, GesneriacecR, Napoleonece, VaccineaSf 

 EricacecB, Epacridece, PyrolacecB, Francoacece, and Monotropecs. 

 Of these, the Lobeliaceae, Campanulacese, and Cyphiacefe were elabo- 

 rated by Prof. Alphonse DeCandolle, the well known son of the dis- 

 tinguished author; the Vaccinefe by Prof. Dunal of Montpelier ; and 

 the tribe Ericeae (the Heath-tribe) was prepared by Mr. Benthara. It 



