48 ME. R. H. BTJElSrE ON THE AOETIC-ARCH 



Plate TV. 



Fig. 9. Section of tbe free edges of two lamellte of the lung-book. , 



10. Section through lamella of lung -book near their base. 



11. Part of the wall of the air-space towards the centre. 



12. Section of wall of air-space towards the side. 



13. Side view of mouth and surrounding parts. The left first and second 



appendages have been removed and the thorax laid open. i. and ii., 

 right first and second appendages ; car., carapace ; eps., epistome; 

 m., mouth ; p.s.t., sense-organ on base of appendage ii. 



14. Ventral sclerites of second and third free segments, viewed from 



inside. 



15. Section of wall of stercoral pocket. 



16. Section of one of the Malpighian tubes. 



17. Section of epithelium of proctodseum. 



Plate V. 



Fig. 18. Ventral surface of abdonien of Fhrynus reniformis, vrith egg-sae. 



19. Young embryo of Phrynus reniformis : surface view. 



20. SiAe view 0? einhrjo oi Phri/?ms anmdatipes, x9. /.o., lateral organ. 



21. Schematic longitudinal vertical section of Phri/nus anmdaiipes, X ■ 'j- 



O.C., median eye; gen.a,., genital aperture; Stc, stercoral pocket; 

 Pr., proctodeum. 



22. Longitudinal section of first four abdominal segments. X -V-- 



23. Longitudinal section through front part of coxal gland and duct. 



On the Aortic- Arch System of Saccohranchus fossilis. By R. H. 

 Btjene, B.A. OxoB., Assistant in Museum, lioyal College of 

 Surgeons, London. (Communicated by Prof. G. B. Howes, 

 F.L.S.) 



[Eead 5th April, 1894.] 



In tropical countries, but more especially in India, where the 

 streams and tanks are liable to become dry in the hot season, a 

 number of the freshwater fishes hare acquired the power of 

 living for a longer or shorter time out of water, and are thus 

 enabled either to migrate to places where water is more abundant, 

 or to bury themselves deep down in the mud to await the re- 

 vivifying rains. Many years ago * reports that fish were often 

 dug up in spots that had been dry for months, or were found 



* For the early literature of this subject see Boake, Journ. Oeylon Branch 

 Asiat. Soc. 1865, and Day, Proc. Zool. Soc. 1868, p. 274. 



