Fig. 140. EchinuH miliaris Leskk. Section of tlie dental system, showing 



the tive pyramids witli tlieir teetli aud the inter-pyramidal muscles. 

 Fig. 141. Echinocyamus angulosus Leske. Section of the dental system. 



the tive i)yraniids with the teeth and the inter-pyramidal muscles. 

 Fig. 142. Echinarachnius Parma Lamck. Section like the preceding. 

 Fig. 143. Lagannm decagonalc Blv. The dental system, entire, seen from 



above. 

 Fig. 144. Chjprastcr reficulafns L. The same. 

 Fig. 14;"). Echinoiijamus angulosus Leske. The same. 

 Fig. 14(i. Arachnoides Placenta L. The same. 

 Fig. 147. Echinarachnius Parma. Lamck. The same. 

 Fig. 148. Encope rmarginata Leske. The same. 



Fig. 149. Clypeastcr reticnlatns L. Crowus of the five teeth, front view. 

 Fig. 150. Clypeastcr reticulatus L. Crown of a tooth seen sidewise. 

 Fig. 151. Echinarachnius Parma Lamck. Crowns of the five teeth, front 



vieAv. 

 Fig. 152. Lagannm decagonalc Blv, the same. 



