CLASSIFICATION OF THE BRACHIOPODA. 55 



II. The position of the Cardinal muscle of King {Adductor brevis of Prof. Owen) is 

 always recognisable in the interior of the articulated genera. In the ventral or dental 

 valve it leaves two large pyriform scars always clearly defined, and extending somewhat 

 in advance of the confluent insertion of the Adductor. In passing to the opposite valve the 

 two divisions of this muscle converge and are fixed in the dorsal or socket valve to 

 a Cardinal process [boss of King), which varies to a very remarkable extent in certain 

 TerebratuliddB, Stringocejjhalus, Camarophoria, Orthis, Strophomena productus &c., while 

 in some forms, from the non-development of this process, the muscular attachment to that 

 valve is less clearly defined. In the un -articulated genera, Discina and Crania, the 

 equivalent of the cardinal muscle has not been ascertained with certainty; it is perhaps the 

 sliding muscle of Professor Owen. 



given by Professor Owen, in his 'Memoir on the Anatomy of the Brachiopoda' (1833), in which it is 

 stated that the muscles which have been termed valvulars pass into the upper part of the pedicle — a state- 

 ment which I am led to suspect may have arisen simply from the superior termination of these muscles, in 

 the specimens examined by this distinguished anatomist, being so close to the upper part of the pedicle as 

 to appear as if attached to it." In 1849 Professor King diagramatically represented the muscular system 

 of Ter. australis, and the position of our adductor and cardinal muscles {adductor longus and brevis of 

 Professor Owen) is clearly exposed ('English Permian Fossils,' pi. xx, figs. 10 — 12). Professor Owen 

 likewise states, that in the year 1846 he left for publication at Naples most of the details on the muscular 

 system he has introduced in the first chapter of this Introduction. In a very useful and interesting manual 

 on the 'Mollusca,' published by Mr. S. P. Woodward (1851), a figure of Ter. australis is given (p. 8) 

 in which the retractors (cardinal muscles) are there termed for the first time (to my knowledge) 

 " muscles by which the valves are opened." However, one year after (1852), Professor M'Coy states in 

 his 'British Pal. Fossils in the Cambridge Mus.,' p. vii of the advertisement, and p. 191 of the letter- 

 press, that he had discovered " that the valves of Terebratula were opened by the action of a pair of 

 muscles, which arise from the middle of the perforated or receiving valve, and the tendons of which are 

 inserted into the internally prolonged entering beak of the entering valve, which thus forms a lever moving 

 on the hinge-teeth as a fulcrum." I have not, however, been able to find where the learned author had 

 published these discoveries, which to claim priority must have been made public before 1846. 



In the short zoological account of the Brachiopoda, published by the learned author of the ' Paleont. 

 Fran9aise,' in the 'Annals des Sciences Nat.,* vol. viii, 1847, some of the muscles seem to have been 

 incorrectly described. 



To conclude this account of the views hitherto published on the muscular system of the genus 



Terebratula, we may mention, that in Dr. Gray's 



,' Catalogue of the Terebratulse in the British ^y-<!^^^^^^^^ -^^^\>i^^ ''^ 



Mus.' (1853), two diagrams by Mr. Woodward ^j;:^^^^ , ^^^^"^^~^^^-^^^C'-x 



illustrate the muscular impressions in the Ter. /^ ^^ia^^^mw^V^"-^ 



australis, and which we have reproduced with Dr. /^ £ o ^^^^^^y^X' '\\ *' 



Gray'spermission, inp.64,figs. 6, 7. Thewoodcut K_, /Q ^] -~^^^^^s^^^ '■M'mi^^^4 l\ 



here appended (fig. I), was likewise drawn for Dr. ) \^^"^^^^^P^^ /^^iiJIjM'/IlP-^^^^^ 



Gray by Mr. Albany Hancock, to which were at- V ^^^^ — ~~~--^ /f^90L} '^T'^^r 



tached the following explanations : a, adductors ; ^=\^ ^^^^^::r:: i;. '^''''Z ^^^^^^'w''^,^- i^^^^ 



r, retractors ; x, accessory retractors ; p,p, pedicle ^^^IT^*-— >^ 40y/W7 /]^^< 



muscles ; z, function uncertain ; o, mouth ; v, -Zi r~~~ 'Z I^^^^'^ 



vent; I, loop; t, dental socket. Fig. I. Waldheimiaflavescens. 



