THE GUT OF NEBALIACEA 17 



nothing escapes thorough digestion. The fore-gut is adapted to the puncturing and sucking of the 

 eggs and the mandibles to holding them in position during these processes. 



Interesting parallels to the development of a large storage chamber when an occasional meal is 

 taken are to be seen in the Decapoda and in the Anaspidacea. In the former group there is a swelling 

 of the anterior region of the cardiac portion of the stomach in all the predatory forms examined, while 

 in Porcellana, which has been shown by Nicol (1932) to be a filter feeder, there is no such swelling. 

 Similarly in the Anaspidacea, Koonunga cursoria, which has been shown by Cannon and Manton 

 (1929) to have 'given up fiher feeding completely', has a long tubular storage section of the fore-gut 

 which is absent in Anaspides and Paranaspides, which are filter-feeding forms. 



In the above three examples the same result has been attained by entirely different means. 



The gut is in more direct contact with the environment than any other internal organ and is thus 

 more subject to the same influences as act upon the external features. The type of food available not 

 only influences the method of capture and the mouth parts, but also the structures which have to 

 deal with it later on. An attempt has here been made to show how the digestive mechanism of the 

 Nebaliacea may be correlated with the habits and habitats of these animals as far as can be deduced 

 from present knowledge of this rare group in which so many evolutionary links are missing. 



The greater part of this work was carried out in the Zoology Department of the University of 

 Manchester while holding the Grisedale Research Scholarship. I wish to thank Professor Graham 

 Cannon and Dr S. M. Manton for the loan of fixed material, Mr G. A. Steven for the living specimens 

 of Nebalia, specially collected along with characteristic elements of their habitat, and all three for 

 much helpful advice and criticism. 



BIBLIOGRAPHY 



Cannon, H. G., 1927. On the feeding mechanism 0/ Nebalia bipes. Trans. R. Soc. Edinburgh, lv, pp. 355-70. 



Cannon, H. G., 1931. Nebaliacea. Discovery Reports, in, pp. 199-222. 



Cannon, H. G. and Manton, S. M., 1929. On the feeding mechanism of the Syncarid Crustacea. Trans. R. Soc. Edinburgh, 



LVi, pp. 175-89. 

 Claus, C, 1889. Organismus der Nebaliiden und Systematische Stellung der Leptostraken. Arb. Zool. Inst. Univ. Wien, 



viii, pp. 1-149, pis. 1-15. 

 Jordan, H., 1909. Die Pylogenese der Filtervorrichtungen in Pylorttsmagen der Malacosiraca. Verb. d. Zool. Ges., Leipzig, 



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 Jordan, H., 1912. Der Magen der hoheren Krebse. Naturw. Wschr. xi. 



Nicol, E. A. T., 1932. The feeding habits of the Galatheidea. J. Mar. Biol. Ass. U.K. 1932, pp. 87-106. 

 Ohlin, 1901. Arctic Crustacea collected during the Swedish Arctic E.xpeditions 1898 and 1899. Bihang Svenska Acad, xxvi, 4, 12. 

 Thiele, J., 1904. Die Leptostraken. Wiss. Ergebn. d. Tiefsee Expedition 'Valdivia', vii, pp. 1-26, pis. 1-4. 

 Thiele, J., 1905. Ueber die Leptostraken der Deutschen Siidpolar Expedition, 1901-1903. D. Siidpolar Exp. ix (Zool. i), 



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