336 



EDWARD S. MORSE ON 



Hancock ('-39) states that in tlie brachium he found 4,000 ch-ri. Wliether this 

 number was based on a definite count or an estimate is not known. In the species 

 studied in the St. Lawrence, and which has alAvays been recognized as identical with the 

 H. psittacea of Europe, I counted only 450 cirri on the brachium of a fully matured speci- 

 men. This leads me to believe that Hancock's figure i.s the result of a misprint and that 

 the number should read 400 and not 4,000. 



Muscles. 



The muscles of many forms of Brachiopoda have been often figured and described, 

 and a number of investigators have given their own interpretation of the functions of 

 these muscles with a terminology of their own, differing, of course, from that of their 

 predecessors. Hancock's names for the muscles of Lingula were \dtiated because he 

 argued from analogy that since tlie Testicardine forms liad an interlocking device to 

 prevent the lateral displacement of- the shells, in Lingula, there being no such interlocking 

 device in tlie shells, the muscles were so arranged as to accomplish the same purpose" 

 He says, " Indeed the attachments of the various muscles [in Lingula] are so distributed 

 around the margin of the peri^dsceral chamber that transverse, longitudinal and diagonal 

 movements are alike guarded against. And perhaps their true functions are^best 

 understood when thus considered in co-operation ; it is then seen that they form a com- 

 plicated complementary system fur the purpose of assisting in adductiug the valves, their 

 various points of attachment and cUfferent inchnations being so arranged, that, in'what- 

 ever state of action they may happen to )je, they will always keep the valves steadily and 

 accurately opposed to each other." In commenting on the names given hy prcA-ious 

 investigators to the muscles of Lingula, Hancock says, " It is necessary to alter "the.se later 

 epithets as they imply what appears to be a false theory, namely : the slidino- of the valves 

 over each other." Owen ('35), to whose terminology he particularly refers and upon 

 which he animadverts, in describing the various muscles of Lingula, says, "The arrange- 

 ments of these powerful adductors are such as to effect the sliding movements of the 

 valves on each other, beside closing the shell, and to compress and variously affect the 

 interposed ^dscera and visceral lacunae with their contained sinuses," and I may add that 

 no words could express more correctly the precise work accomphshed bv these muscles, 

 for they cause not only the '' transverse, longitudinal and diagonal movements" of the' 

 sheU, and that in a more vigorous way than even Owen dreamed of, Init tliey do com- 

 press and variously affect the interspersed viscera and tlie circulation, as xvill he seen 

 farther on. 



