544 PROCEEDINGS OF THE ACADEMY OF [Dec, 



of a coil in the ancestral shell, which may have been altered by 

 caeogenetic variation and the resorption of parts. The structure 

 and disposal of the growth lines, the simple character of the lateral 

 pouches and their small size in proportion to the size of the egg and 

 larva, indicate that they are caused by something other than a 

 coil. Trochus, Natica, A r assa, Eolis, or Ammonite and nautiloid 

 protoconchs do not seem to differ much from the structure described 

 above. 



Literature. 



I >all, W. H. 1890. Tertiary Mollusks of Florida, Trans. Wagner Free Institute, 



III, 1S90, p. 295. 

 Fisher, \Y. K. 1904. The Anatomy of Lottia gigantea Gray, Zoologischr 



Jalcrbucher, Abth. f. Anat,, Vol. 20. pp. 1-86, pis. 1-4. 

 Grabau. 1903. Studies on Gastropoda, American Naturalist, Vol. XXXVI 



p. 919; XXXVII, No. 440, p. 515. 

 Morse, E. S. 1910. An Early Stage of Acmaea, Proceedings of the Boston 



Society of Natural Histonj, Vol. 34, No. 8, pp. 313-323, February, 1910. 

 Patten, W. 1886. The Embryology of Patella, Arbeiten aus dern Zoolog- 



ischen Institute der Universitdt Wien, Vol. 6, pp. 149-174, pis. 1-5. 

 Pelseneer, Paul. 1906. In Lankaster's Treatise on Zoology, Part V, Mollusca, 



A. and C. Black, London, 1900. 

 Verrill, A. E. 1896. The Molluscan Archetype considered as a Veliger-like 



Form, with discussions of certain points in Molluscan Morphology, American 



Journal of Science (4th Series), Vol. 11, No. 8, August. 1896. 



