Report of the State solo gist. 



543 



ZAngula anatina : cardinal 

 area of pedicle-valve, after Kino, a, 

 deltidium; 6, deltidial ridges; c, delti- 

 dial callosities; <L areal borders. 



oular pedicle protruding from between the beaks of the two 



valves. The pedicle-valve has a dis- 

 tind cardinal shelf or area, divided 

 Longitudinally by a depression widen- 

 ing from the apex anteriorly, and 

 termed by King the "deltidium." 

 This, according to Professor King, is 

 usually not well developed, and in 

 the average specimens of L. anatina found in museum collections, 

 appeal's to be partially or quite wanting, from accidental causes. 

 The deltidium is bounded at the sides by elevated ridges, which, 

 at the anterior ends, are each developed into a small callosity. 



Muscular impressions numerous, but usually indistinct. In the 

 recent species they are twelve in number upon each valve, and 

 are somewhat unsymmetrical in 

 their arrangement. They may 

 be designated as follows: The 

 umbonal impressions (g), pro- 

 duced by a single muscular band 

 passing directly across the 

 cavity of the shell near the 

 beaks, and by their contraction 

 opening the valves ; the lateral 

 impressions, which are produced 

 by three pairs of muscles, the 

 anteriors (j) passing from near 

 the lateral boundaries of the 

 visceral area on the "pedicle- 

 valve, forward to the anterior 

 extremity of this tract on the 

 brachial valve ; the middles (k) 

 passing in just the opposite di- 

 rection, from the anterior region 

 of the pedicle- valve to the lat- 

 eral region of the brachial valve ; 

 the externals (I) passing from the 

 ante-lateral region of the pedicle- 

 valve to the post-lateral region 



Fig. 229.— Lingula anatina after Hancock. 

 p, pedicle; g, umbonal muscle; h, centrals; 

 i, transmedians; j, k\ I, laterals (J, ante- 

 teriors, fc, middles, I. externals); e, heart; 

 o, mouth, a, alimentary canal; z, anus. 



valves forward and backward. The central impressions (h) are 



95 



of the 

 muscles 



brachial valve, these 

 serving to move the 



