700 MR. F. E. BEDDARD ON THE [June 16, 



and unpaired. In an example of Dasyurus onaugcei the anterior 

 series of intercostals were all paired at their origin excepting the 

 last three in front of the diaphragm Avhich arose by a single 

 median trunk, each trunk dividing of course into the right and 

 left intercostal of its segment. After the diaphragm the intercostals 

 were at least chiefly paired in origin. I have figured these 

 arteries in the genera of Oarnivora *, ffelictis, Gdlictis, and 

 J^uricata, where they arise as paired trunks. There exist, 

 naturally, descriptions of these arteries in many mammals t ; 

 but there is need for further collection of facts before they can be 

 utilised for systematic purposes, for which purposes, however, it is 

 obvious from what has already been said that their variability 

 will have to be taken into careful consideration. In the mean- 

 time I venture to record such facts as I have happened to 

 ascertain myself, without attempting anything like a revision of 

 the existing knowledge of these arteries. 



I have also ascertained some facts with regard to the venous 

 system of Chiromys, and I take this opportunity of incorpoi-ating 

 some facts concerning the venous system of Microcebus smithii, of 

 which there is apparently no published information so far as I 

 ■can discover. I dissected the postcaval vein (text-fig. 153) in both 

 of the adult specimens. It was a single vein throughout and lay 

 as usual to the right of the aorta. The renal veins as is also usual 

 were asymmetrical, the left lying some way behind the right. The 

 mode of origin of the ovaiian veins varies somewhat in mammals. 

 In Chiromys the vein supplying the right side arose from the 

 postcaval not far in front of the posterior bifurcation of the 

 latter. The left vein, on the other hand, arose from the left 

 renal, as is often the case. This particular asymmetry is very 

 general in mammals, but it is not always the case that the right 

 ovarian vein flows into the postcaval so far down. In the male 

 specimen there was an interesting difierence in the place of 

 influx of the two spermatic veins. That of the right side 

 corresponded on the whole with the right ovarian vein. But 

 that of the left side did not arise from the left renal vein but 

 from the postcaval behind that vein, though some way in front of 

 the point of origin of the right spermatic vein. The homologue 

 of the ovarian vein of the female was, however, also present on 

 the left side. The renal vein, in fact, received a branch at a 

 point exactly corresponding with the entrance of the left ovarian 

 vein in the female example. But this vein ended in the muscular 

 parietes and was evidently concerned alone with the venous 

 system of the lumbar parietes. These facts ai-e illustrated in the 

 accompanying text-figure. 



In Microcehiis the arrangement of the corresponding veins was 



* " Ou the Anatomy of Selietis personata" P. Z. S. 1905, vol. ii. pj). 27, 28 

 text-figs. 11, 12. 



f E.ff. in OrnWwr'hynclms, Mannevs-Smitli, P. Z. S. 1894, p. 714; Manatee, 

 Mul-ie, Trans. Zool. Soc. vol. viii. pi. 26, fig. 44; Horse, Chauveau & Arloing, Traite 

 ■d'Anat. Comp. Anim. clomest. 1871, f. 555, and manj' special treatises. 



