Prof. W. King on Spirifer cuspidatus. 21 



pressions there is situated a smaller pair, neither well marked 

 nor distinctly defined, 5, h ; and the rather prominent ridge, 

 c, immediately behind the latter, I suspect represents another 

 pair. 



Besides the preceding, other muscular impressions are indi- 

 cated by the longitudinal lines on and near the cast of the 

 canal (fig. 32 a) belonging to the transverse septum*. These 

 markings are important as clearly showing that the canal 

 served as a muscular support, though such an office must have 

 been limited to its open or terminal portion. The canal, from 

 what has been adduced in the previous section, bears evidence 

 of its older portion having become gradually closed up by the 

 deposition of shelly matter in its interior. 



It is not altogether safe to identify the different muscles 

 which belonged to S^pirifer cuspidatus with those known to 

 characterize certain recent Palliobranchs, as made known by 

 various writers, including myself f. I may, however, be 

 allowed to offer a few suggestions in this direction. 



The impressions lettered a, I have little doubt, represent the 

 ventral pedicle-muscles ; those marked h may, I am led to 

 suspect, have been produced by the valvulars (" adductors ") ; 

 and those distinguished by the letter c are probably the repre- 

 sentatives of the cardinals. 



There is some difficulty with the muscles belonging to the 

 canal ; and this is increased by the uncertainty that attaches to 



* A representation of the canaHferous septum, as indicated by the cast 

 of it, is given in fig. 33. 



t The description wliich I have published, illustrating the muscular 

 system of Waldheimia australis, first appeared in the ' Ann. & Mag. Nat. 

 Hist.' vol. xviii., July 1846, and was copied, with the addition of some 

 figures, in my ' Monograph of Permian Fossils,' pp. 73-76 (1850). It was 

 the first one in English giving an account of a pair of muscles which pass 

 from the inner surface of the perforated valve to the process (cardinal) 

 in the centre of the hinge of the opposite valve. But it came to light 

 some years afterwards (see Gratiolet, Academic des Sciences, Paris, 

 July 11, 1853 ; and Davidson, Annals & Mag. Nat. Hist. ser. 2. vol. xvi. 

 December 1855) that I had been anticipated by Prof. Quenstedt, who, in 

 1835 (Wiegmann's Archiv, vol. xi. pp. 220-222), pointed out the occur- 

 rence of the same muscles in Rhynchonella psittacea. Mr. Davidson, who 

 has taken much pains in elucidating the history of the discoveiy of this 

 point, and making known the general myology of the Palliobranchs (see 

 Introduction to ' Monograph of British Fossil Brachiopoda,' pp. 53-56 ; 

 and 'Annals,' above cited), has faithfully credited the various writers who 

 have treated of the subject with the merits to which they are individually 

 entitled. With the exception of some discoveries explaining the mode of 

 attachment of the pedicle (or, rather, its capsule) to the surface of the 

 umbonal cavity, and proving the existence of certain accessory muscles in 

 the same part, nothing of importance in palliobranchial myology has been 

 made known since the original publication of my description. 



