337 [Wilder 



quoted, evidently thinks it is not of class value in the determin- 

 ation of homologies among radiates ; Parker,' 292, 3, associates 

 "histology " and " function " in such a way as to indicate that he re- 

 gards their morphical value as less than that of relative position. 

 But it does not appear that due attention has been given to the 

 problem suggested by the following considerations: 



It is certain that a tendon may ossify, as in the skelea of fowls 

 and the so-called " marsupial bones," so that what was at one time 

 fibrous becomes osseous in structure ; the same, however, holds true 

 of the membrane bones of the skull, and of course, no one questions 

 the homology of a bone with its own pre-existing cartilage, or with 

 that of another individual or part of the same indiviudal ; and upon 

 this ground alone no objection arises to Owen's view of the meke- 

 syntropic homology of the marsupial bones 1 (63, 2, 356); so, too, 

 the capsule of the eye-ball is generally admitted to be homolo- 

 gous throughout the vertebrate branch, although it is fibrous in 

 man, gristly in the turtle, and bony in the tunny (Thynnus) (63, 

 1, 26). But is it possible for a muscle to be the true homo- 

 logue of a ligament ? as Duvernoy thinks of the human subclavius and 

 the costo-coracoid ligament of the gorilla 2 ; and still more, can 

 muscle correspond to bone ? as is assumed by Humphrey and Huxley 

 of the clavicle and Pouparts' ligament (72, 77 and 78, < 37). Coues 

 alludes to a theory (apparently a notion of his own) tliat certain om- 

 ozonio muscle* may be antitropically represented in pelvico-sacral 

 ligaments. It might be urged that since in a typical muscular organ, 

 muscle and tendon are continuous parts, and since the belly of a given 

 muscle may be of very different lengths in different species, they are 

 in one sense homologous structures, but evidently there should be a 

 better understanding among homologists respecting the morphical 

 value of histological composition. 3 



Mode of Development. 



Respecting the morphical value of this attribute of organs and an- 

 imals, the most widely diverse opinions have been held. Owen has 

 constantly urged its slight importance in comparison with, adult struc- 



1 As to the rudimentary fibro-cartilages of Thylacinus, see Owen, Proc. Zool. 

 Soc, 1843, p. 148. 



2 Archives du Museum, Tome viii ; referred to in 38, 357. 



s Goodsir alludes to this question (297, 397), when he says, " Tissue is subordinate 

 to form," and Huxley mentions without comment, the extraordinary fact that the 

 outer serous stratum, or epiblast, of the beginning embryo, gives rise to thQ two 

 anatomical and physiological antipodes, epidermis and cerebrospinal nervous cen- 

 tres (78, 10). 



PROCEEDINGS V &. N. H. — VOL. XIV. 22 MAY, 1872. 



