THE " POEUS GENITALIS " IN THE MTXINID^. 487 



EXPLANATION OF PLATE 31. 



All the figures represent the hyobranchial skeleton of early tadpoles, the 

 measurements of which are given on p. 475. Except in figs. 3 and 6 the 

 ceratobranchials are shown only on one side of the figure, or are not shown 

 at all. All figures exhibit the dorsal aspect ; and the magnification is expressed 

 by the usual symbols in the Plate. 



Fig. 1. Bombinator igneus. 



2. Rana temforaria. 



3. Microlnila ornata. 



4. Leptohrachium Hasselti, 

 6. Pseudis paradoxa. 



6. Oxyglossus l<svis. 



7. Chiroleptes platycephalus. 



8. Pelobates fuscus. 



Reference Letters. 

 ca. Anterior copula (fig. 1). 

 cb} First ceratobranchial, 

 ch. Ceratohyal. 



cp. Posterior copula in fig. 1 ; the copula in figs. 2-8. 

 hbr. Hypobranchial plate. 



I. Ligamentous band in the hyoglossal sinus. 

 Is. Laryngeal sinus. 

 fr. Pars reuniens. 

 s. Space at the side of the copula. 



s.^ Space between the anterior copula and the pars reuniens (fig. 1). 

 sp.* Spiculum of the fourth branchial arch. 



The "Porus genitalis" in the Myxinidae. By E. H. Burne, 

 B.A., Anatomical Assistant in the Museum o£ the Eoyal 

 College o£ Surgeons of England.* 



[Read 20th January, 1S98.] 

 (Plate 32.) 



Since the days of Johannes Miiller f no detailed investigation 

 has been made into the coarse anatomy of the cloacal region of 

 the Myxinoids ; subsequent anatomists % having for the most 



* Communicated by Prof. G. B. Howes, Sec. Linn. Soc. 



t Johannes Mailer, " Untersuch. iiber die Eingeweide der Fische," Abhl. d. k. 

 Akad. Wiss., Berlin, 1843, p. 113. 



\ Vogt & Pappenheim, "Organes de la generation des Vertebres." Ann. Sci. 

 Nat. ser. 4, xi. 1859, p. 345 ; W. Miiller, " Urogenitalsystem des Amphioxus u. 

 der Oyclostomen," Jena. Zeitschr. ix. 1875, p. 109. 



35* 



