ON THE GENERAL MORPHOLOGY OF THE MYXINOID FISHES. 753 



evident from a mere examination of Retzius' statement that if both hearts are to 

 discharge simultaneously, there cannot be any lateral movement of the anterior knob. 

 Greene's description in fact applies also to Myxine. 



Perhaps I may here make a preliminary announcement on another question discussed 

 by Retzius in the above paper. This is as to whether the caudal hearts transmit blood 

 from the large subcutaneous space to the veins. Retzius concludes, on evidence 

 communicated to him by Klinckowstrom, that it does, and this has since been amply 

 confirmed both by the latter and by Greene.* In studying the question from a new 

 point of view, i.e. by serial sections, it is easy to demonstrate beyond all question that 

 the caudal hearts are in communication with the subcutaneous sinus. The question 

 now arises — How does the blood enter the latter sinus ? Beyond Retzius, who simply 

 mentions the matter, only Klinckowstrom has touched on this point. I may therefore 

 mention that there are further communications anteriorly between the sinus and the 

 large internal vascular cavities of the snout which provide ample opportunity for 

 the entrance of blood into the subcutaneous sinus. In this connection the reader may 

 refer to my description of the communications between the afferent branchial vessels 

 and the pleural sacks (5, p. 325). 



LITERATURE. 



[In this list only those works are included which contain original observations on the muscles of Myxinoids.] 



1. Allis, Anat. Anz., Rd. xxiii. p. 259, 1903. Transversus oris, Palato-ethmoidalis profundus, Cranio- 



hyoideus, Quadrato-palatinus, Palato-coronarius, Constrictor pharyngis. 



2. Aters, Biological Lectures at Wood's Holl, 1893 [vol. ii.], p. 125, Roston, 1894. Muscles of the " tongue." 



3. Ayers and Jackson, Jour. Morph., vol. xvii. p. 185, 1901. Reprinted, Bull. Cincinnati Univ., 



Ser. II., vol. i., No. 1, 1900. Muscles of the "tongue." 



4. Cole, Trans. R. Soc. Edin., vol. xli. p. 749, 1905. 



5. Cole, Anat. Anz., Rd. xxvii. p. 323, 1905. 



6. Furbringer, M., Gegenbaur's Festschrift, vol. iii. pp. 613 and 627, Leipzig, 1897. Parietalis, Rectus, 



Ohliquus, Tentacularis posterior. 



7. Furbringer, P., Jena. Zeits., Rd. ix., N.F., ii. p. 1, 1875. Section A, § 2, published separately as an 



Inaug. Diss., Jena, 1874. General description of the muscles. 



8. Greene, Amer. Jour. Phys., vol. iii. p. 366, 1900. Science, vol. xv. p. 342, 1902. Cordis caudalis. 



9. Grenacher, Z.f. w. Z., Rd. xvii. p. 587, 1867. Also published as an Inaug. Diss., Leipzig, 1867. Parietalis. 



10. Madrer, Morph. Jahrb., Rd. xxi. p. 509, 1894. Histology of Parietalis. 



11. Muller, J., Abh. Ah. Berlin, 1834, p. 243, 1836. General description of the muscles. 

 12. Abh. Ak. Berlin, Jahr 1843, p. 167, 1845. Sphincter cloacae. 



13. Pollard, Anat. Anz., Rd. ix. p. 349, 1894. Zool. Jahrb., Abt. Morph., Bd. viii. p. 379, 1895. Muscles 



of tentacles. 



14. Retzius, A. A., Kgl. Vet. Akad. Handlgr. Stockholm, p. 408, 1824. German translation, Isis, p. 1013, 



1825. General remarks on the muscles. 



* Cp. also Favaro's recent note. 



