118 PALEONTOLOGY. 



the conical, pointed, homy teeth of Myxinoids and Lampreys 

 in that class : and the absence of any other hard part in the 

 strata containing the Conodonts tallies with the condition of 

 the cartilaginous skeleton ; hut not more than it does with 

 the like perishable soft condition of annelidous worms and 

 naked mollusks. Rhinodon has very small teeth, " en brosse," 

 of a simple conical recurved form: there are 12 or 13 teeth 

 in each vertical row, and about 250 such rows in each jaw ; 

 so that each fish may have from 6000 to 7000 teeth. But 

 the teeth of Rhinodon have not the basal extensions and 

 processes of many of the Conodonts; and the teeth of all 

 known Cyclostomes, besides being considerably larger, are 

 much less slender and are less varied in form than in the 

 Conodonts. This minuteness of size, with the peculiarities 

 of form, supports a reference of the Conodonts rather to some 

 soft invertebrate genus. Certain parts of small Crustacea — 

 e.g., the pygidium or tail of some minute Entomostraca — 

 resemble in shape the more simple Conodonts ; but when we 

 perceive that these bodies occur in thousands, detached, with 

 entire bases, and that any part of the carapace, or shell of an 

 Entomostracan or other crustacean, has been rarely detected 

 in the lower Silurian Conodont beds, it is highly improbable 

 that they can have belonged to an organism protected by 

 a substance as susceptible of preservation as their own. 

 Much more likely is it that the body to which the minute 

 booklets were attached was as soluble and perishable as the 

 soft pulp upon which the Conodont was sheathed. The writer 

 finds no form of spine, denticle, or hooklet, in any Echinoderm, 

 and especially in any soft-bodied one, to match the Conodonts ; 

 and concludes that they have most analogy with the spines, 

 or hooklets, or denticles of naked Mollusks or Annelides. 

 The formal publication of these minute ambiguous bodies of 

 the oldest fossiliferous rocks, as proved evidences of fishes, is 

 much to be deprecated. 



