On the Classification of Birds. lOl 



intequilateral, umbones prominent, oblong in form, being 

 somewhat produced posteriorly ; the ligament is external ; 

 teeth in right valve apparently three, in the left two, all 

 cardinal ; inner surface subpellucid, white ; pallial line with 

 a conspicuous sinuosity. 



Several examples, but only a very few in mature condition, 



EXPLANATION OF THE PLATES. 

 Pla-Te L 



Fig. 1. Nassa {Hima) ischna. 

 Fig. 2. Drillia theoreta. 

 Fig. 3, Mangilia chilosema. 



Fig. 4. galigensis. 



Fig. 5. perlonga. 



Fig. 6. theskeloides. 



Fig. 7, ClatlmreUa G'Malegi, 



Fig. 8. Latinis (Peristernia) pagod(Bfonnis. 



Fig. 9. Erato olivaria. 



Fig. 10. Scalaria {Cirsotrema) hidryma. 



Fig. IL {Cortst(mtia) Sfandciii. 



Fig. 12. Cerithiopsis (Seila) bandorensis, Melv. 

 Fig. 13. Actfsnpyramis Psyche. 

 Fig. 14. Odostomia eutropia. 

 Fig. 15. Pyrgulina epentmmidea. 

 Fig. 16. glycisma. 



Plate II. 



Fig. 1. Fusus Toicmendi. 



Fig. 2. MUra (Pusia) Elizce. 



Figs. 3, 3 a. Mitra {Costellaria) revelnta. 



Fig. 4. Natica Pons"nbyi. 



Fig. 5. Lncuna tenuistriata. 



Fig. 6. Pridtrochiis. sepidchrcdis. 



Fig. 7. Mactrinula tryphera. 



Fig. 8. Lucina ( Codakia) angela. 



Figs. 9, 9 o. <Jryptodon victorialis. 



Fig. 10. Scintilla callipareia. 



Fig. 11. Uiplodonta holosphcBva. 



Fig. 12. ? CEd'dina asiatica. 



VI. — Observations on the Classification of Birds. 

 By Dr. R. W. Shufeldt *. 



In former papers of mine the classification of various groups 

 of birds has been treated, their osteology, as a rule, being tlie 

 anatomical system employed and referred to for the purpose. 



* From the * Proceedings of the Academy of Natural Srienees of 

 Philadelphia,' 1898, pp. 489-499. Read by title at the Sixteenth Con- 

 gress of the American Ornithologists' Union, at the United States National 

 Museum, Washington, D.C ., 17th November, 1898. 



