ON THE STRUCTURE OF iENIGMA ^NIGMATICA. 293 



11. MiTiiA, S, B.— "The Cryslalliiie Style of Lamellibranchia," 'Quart. 



Journ. Micr. Sci.,' N. S., xliv, 1901. 



12. Morse. — " Remarks on tlie Relations of Anomia," ' Proc. Boston Soc. 



Nat. Hist.,' xiv, 1871. 



13. Pelseneer, P. — "Contribution a I'etude des Lamellibranches," ' Arch. 



de Biol./ xi, 1891. 



14. Pelseneer, P. — "Mollusca," Laukester's 'Treatise on Zoology,' part v, 



1906. 



15. Riuewood, W. G. — "On the Structure of the Gills of the Lamelli- 



branchia," • Phil. Trans. B.,' cxcv, 1903. 



16. Sassi, M. — "Zur Anatomic von Anomia ephippium," 'Arb. zool. 



Inst. d. Univ. Wien.,' xv, 1903, p. 81. 



17. Sharp, B. — " On the Visual Organs in Lamellibranchiata," ' Mitlh. Zool. 



Stat. Neapel,' v, 1884. 



18. Woodward, S. P.— 'Ann. Mag. Nat. Hist.,' xvi, 1855. 



EXPLANATION OF PLATES 15—17, 



Illustratiug Prof. G. C. Bourne's paper on ''The Structure 

 of Enigma cenigmatica, Chemnitz: a Contribution 

 to our Knowledge of the Anomiacea." 



Lettering in all the figures. 



ad. Adductor muscle, an. Anus. up. Aperture between the right and 

 left renal sacs, a.r.p. Anterior retractor pedis muscle, br.g. Brancliial 

 ganglia, bi/.c. Byssus cavity, by.l. Lamella of byssus. by.lm. Laminae of 

 byssogenous gland, by.pl. Byssus plate, c.cm. Cerebral commissure, c.d. 

 Ciliated discs, c.fl. Latero-frontal cilia of gill filaments, c.fr. Prontal cilia. 

 c.s. Chitinous skeleton of gill filaments, c.v. Ventral cilia on velar filaments. 

 en. Cornea, cry. Caecum of crystalline style, db^. Right external demi- 

 branch. db". Right internal demibranch. db^. Left internal demibranch. 

 dU^. Left external demibranch. ep.ext. External epithelium, e.s. Pallial eye 

 spots. /. Foot. (/I.e. Gland cells, go.a. Anterior lobe of left gonad, go. I. 

 Posterior lobe of left gonad, go.r. Right gonad, int. Small intestine, inl^. 

 Large intestine, k.cn. Concretions in cavity of kidney, l.ep. Left cerebro- 

 pleural ganglion, l.ep. Left excretory pore, l.f.r. Right labial folds or 

 palps, l.gd. Left gonoducal opening into kidney, la.l. Left labial groove. 

 Ig.r. Right labial groove, li. Liver, li.d. Hepatic ducts. Lie. Left kidney. 

 In. Lens of eye. l.p.g. licft pericardial gland, l.rp. Left reuo-pericardial 



