552 PROF. G. B. HOWES ON SOME 



canal. Unfortunately, subsequent investigation has not borne 

 out these statements *. 



The urinary and genital pores of the Teleostei open upon the 

 exterior, as is well known, either independently or through, the 

 mediation of a common urino-genital sinus, and the two orifices 

 may, in some of the first-named cases, be embraced by a tegu- 

 mental fold suggestive of a vestige of the sinus named. In view 

 of the researches, more especially of Huxley, Balfour, and 

 Jungersen, already recapitulated, it can hardly be doubted that 

 the genitalia of the Ganoids and Teleostei conform to a common 

 type, variable in nothing more than degree of inter-communica- 

 tion between the genital and urinary ducts. That tlae cystoariau 

 condition, as exemplified by Lepidosteus on the one hand and tlie 

 majority of living Teleostei on the other, would appear to have 

 resulted from a parallelism of modification is, I think, suffi- 

 ciently clear. 



I have shown reason {ante, p. 548) for adhering to Balfour's 

 belief that the generative ducts are homologous in both sexes of 

 Teleostei ; and if it be true of them it must be so of the Granoidei 

 also. If this is, as I believe, sound, it is fair to assume, in con- 

 sideration of the facts of anatomy and development recapitulated 

 in the foregoing pages, that there must have existed a piscine type 

 in which the male apparatus was in the elasmoarian condition — 

 in which, that is to say, the so-called " vas deferens " was au in- 

 complete tube with a wide ostium. No ichthyotomist will need 

 to be reminded that this is precisely the condition of the parts 

 in the Sturiones, except that no one has yet succeeded in proving 

 that the duct transmits the spermatozoa f. In the Sturiones the 

 genital glands extend throughout the whole length of the post- 

 pericardiac coelom; and Max Weber's discoveries among the 

 Salmonoids % show that in the higher Osteichthyes we have to deal 

 with an abbreviation of this condition. In fact, the Sturgeons 

 present us with exactly that which my hypothesis demands. 

 Balfour and Parker have concluded § that " the most j^rimitive 



* Cf. Ewart, Journ. Anat. & Pbys. vol. x. p. 488 (1876). 

 i' Cf. Hyrtl, Denkschr. Akad. Wien, 1855, pp. 1-5; Johannes Miiller (Hyrtl 

 cit.), and Jungersen, loc. cit. pp. 185- 187. 



X And especially Argentina, see Morph. Jahrb. Bd. xii. p. .395. 

 § Phil. Trans. 1882, part ii. p. 423. 



