No. 44^.] 0/?AL BREATHING VALVES OF TELKOSTS. 157 



apparently had no mandibular valve, yet. tioni tlic shape ot the 

 mouth, there was every reason to expeet a >niall one. Kinally 

 in a large specimen of Semotiliis atroiiiiuiilatn.s it was ^.ee^ that 

 the place of the valve was taken by several rows ot tall [)aj)ill;r. 

 (Fig. 6, d. ) This was found 



to be the condition in all the ///// - 

 minnows where the mandibu- ^ "^'^ 3^^^ 



lar valve seemed absent. q /^/"^^A^ 



The function of the papillcE 8^° jgiTO ^ 

 may be to aid in the finding ^ ^ 



of food. The best develop- Ki<.6-Kormsof papill.i „ setifom. ; verti- 

 ment of papillae seems to be cal section and surface view of the flattened 



among the bottom feeders, vaLr ' ' 

 where such sense organs 



would be most useful. Another modification of the valves is in 

 the pigment which is frequently found in one or both valves. 

 The pigment spots may be regularly arranged or scattered like 

 the papillae the arrangement varying with the species. 



Some valves are further distinguished by rugae or folds or by 



very thin and transparent margins or both as m 

 Ambloplytes gnmiens (Fig. 7). 



As before stated, the valves are not ever of quit 

 Their size and shape are dependent on the size and 

 mouth. For instance, in the case ot the Silurida 

 the mouth is terminal, practically hori/.onial an 

 For this reason it does not need to be oix-ned tar 

 requisite amount of water, therefore the valves ; 

 crescentic but only of moderate depth. (/. e. the ( 

 attachment to margin). The mouth being horizont 

 gitated stream strikes the two valves with about 

 therefore, both must be well developed. 



