On the Classification of ^trds, lOl 



inaequilateral, 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 I. 



Fiff. 1. Nassa (Hima) ischna. 

 Fig. '2. Drillia theoreta. 

 Fig, 3, Mangilia chilosema. 



Fig. 4. galigensis. 



Fig. 5. perlonga. 



Fig. 6. fheskeloides. 



Fig. 7. Clathurella G'Maleyi. 



Fig. 8. Lnfirus (Perisfernia) pagodcefonnis. 



Fig. 9. Erato olivaria. 



Fig. 10. Scalaria {Cirsofremn) hidryma. 



Fig. 11. (Constanti(i) Standeni. 



Fig. 12. Ceritluopsis {Seila) bandorensis, Melv. 

 Fig. 13. Actmopyramis Psyche. 

 Fig. 14. Odostomia eutropia. 

 Fig. 15. Pgrgiilina epentromidea. 

 Fig. 16, glycisma. 



Plate II. 



Fig. 1. Fusi/s Toicnsendi. 



Fig. 2. Mifra (Pusin) Elizte. 



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



Fig. 4. Natica Ponsonhyi. 



Fig. 5. Lacuna tenvistriata. 



Fig. 6. Priotroclms sepulchrcdis. 



Fig. 7. Mactrinula tryphera. 



Fig. 8. Lucina (Codakia) angela. 



Figs. 9, 9 a. Cryptodon vicforialis. 



Fig. 10. Scintilla callipareia. 



Fig. 11. Diplodonta holosjihcera. 



Fig, 12. ? CEdnlina 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 the 

 anatomical system employed and referred to for the purpose. 



* From the ' Proceediufi^s of the Academy of Natural Sciences of 

 Philadelphiii,' 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. 



