August 17, 1900.] 



SCIENCE. 



249 



both upper and under valves, and the con- 

 cavity of the latter is about twice as great 

 as the convexity of the upper valve. 



Perhaps a better idea of the form and 

 other features of the lower valve may be 

 understood by the following : Take an 

 elevated limpet-shell that is circular, or 

 nearly so in marginal outline with an 

 apex that is central. Cover the outside 

 with closely-set radiating lamellae much 

 elevated or produced, standing up at a 

 right angle from the surface of the shell ; 

 the lamellae as thin as writing paper and 

 projecting beyond the extreme margin or 

 periphery. Now reverse this limpet-shell 

 so that the concavity will be uppermost, 

 and press it firmly into a rather compact 

 clayey sea-bed and the general aspect of the 

 lower valve of the Radiolite we are consid- 

 ering, when in situ will be seen, and the 

 function of these external lamellae sug- 

 gested. Whether the lamellse, which are so 

 closely set that the interspaces are about 

 as narrow as the lamellae are thin, are of 

 calcareous or chitinous matter is a point for 

 discussion. The texture of their surfaces, 

 character of fracture, slight prismatic re- 

 flections and the fact that they are ap- 

 parently less perishable than the other por- 

 tions, favor the latter or chitinous character. 



There are no indications tending to show 

 that the lamellae were inclosed by an ex- 

 terior wall, which would make them septae 

 or partitions, and the inter-spaces cells. 

 The lamellar as well as the other exposed 

 parts are much discolored by ferro- oxide 

 making it difiicult to determine, so far as 

 color is involved, whether the lamellae are 

 of a calcareous or ligamentary substance, 

 though the latter is suggested. 



" The foliations of the lower valve," of R. 

 fleuriausus, according to Woodward, "are 

 sometimes as thin as paper and several 

 inches wide. " 



In the remains from the tunnel these are 

 about five-eighths of an inch in width. 



In the related Chamadce we find the 

 various species fix their shells (lower 

 valves), by means of a limey deposit, the 

 same as the substance of their shells, to 

 hard surfaces, cobble-stones, boulders, fixed 

 rock, coral-fronds and to the surfaces of 

 other shells. The grain, texture and lack 

 of density in the ordinary clays are not 

 favorable to attachment by a flat or hori- 

 zontal calcareous deposit. The remarkable 

 lamellar development in the Badiolites 

 whether epidermidal or calcareous, meets 

 this character of sea-bed, by the projection 

 of the lamellae into the clay, and furnishes 

 an interesting illustration of special adapta- 

 tion to peculiarities of habitat or station, for 

 by these lamellae which cover the entire 

 surface (presumably) of the under valve, 

 fixity is obtained in an effective manner. 



These forms probably lived where patches 

 of the sea-bed of a clayey character pre- 

 vailed, at a depth below the agitation of 

 the water during storms. 



For a more thorough determination of 

 the characters of this Radiolite, which for 

 convenience may be called R. Hamlini, 

 further material is awaited. While the 

 conditions of the specimens thus far ob- 

 tained does not admit of a complete diag- 

 nosis, they are nevertheless sufficient to in- 

 dicate the generic relations. These tunnel 

 fossils point to relationship between the 

 clays in which they occur, and the Walalla,* 

 Mendocino county beds visited by Dr. G. 

 F. Becker. The Walalla beds were found 

 to contain fragments of the rare Corallio- 

 chama Orcutti White, previously discovered 

 by Mr. C. E. Orcutt at Todos Santos Bay, 

 Lower California. C. Orcutti occurs at La 

 JoUa, San Diego county, where specimens 

 were collected some years ago by Mr. Ham- 

 lin. 



Dr. Becker's Walalla collection included 

 other species as well as Coralliochama, and 



* Walalla is the Indian name : Gualalla, the U. S. 

 PostofSce title. 



