Report of the State Geologist. 



48? 



tial modification. In the .middle line of the pediole-valve is a 



narrow oval impression of the add/wtor rrvuscle, which La divided 

 medially into two sears; at the sides are two pairs of sears, the 

 larger in front (didrcctors), the smaller behind (pedicle-muscles). 



Fig. 77.— Muscular system of Lingula analina: a, pedicle-valve; b, brachial valve; b, parietal 

 scar; g, umbonal muscle; i, transmedians: h, centrals; j. k, /, laterals (J, anteriors: fc. middles; 

 I, externals). (Davidson.) 



Occasionally the scars of a small accessory pair of diductors are 

 found just behind the adductor scars; and behind these is an 



Fig.78.— Craniella 

 Hamiltonice. The 

 attached valve, 

 showing the anterior 

 and posteror ad- 

 ductor scars. 



Figs 79, 80.— Interiors of the pedicle and 

 brachial valves of Rhynclionella (Hemi- 

 thyris) psittacea; f, foramen; d, deJtidial 

 plates; t, teeth; t', dental sockets; p, 

 pedicle muscle; a, adductors; r, diduct- 

 ors; o, ovarian markings; c, crura; s, 

 septum. 



Fig. 81.— Interior of the 

 pedicle valve of Orthii 

 Clytie, showing the pedicle, 

 adductor and diductor scars. 



undivided scar of the pedicle-muscle. In the brachial valve there 

 are four undivided adductor scars in two distinct pairs, one the 

 anterior, the other the posterior pair. This arrangement of the 



39 



