AM Verrill — Study of the family Pectinidm. 93 



EXPJ.ANATION OF PLATES. 



All the drawings on the following plates were made from nature 

 by Mr. A. Hyatt Verrill, except figs. 5 and 6 of pi. xviii, and fig. 7 

 of pi. xix, which were drawn by J. H. Emerton, and figures 1-5 of 

 pi. xix, which are copied from Dr. R. T. Jackson. 



Plate XVI. 



Figure 1. — Cyclopeden simplex V., sp. nov. Right valve, x 15. 



Figure 2. — Ghlamys Islandica, j'oung. Left valve, x 8. 



Figure 3. — The same, somewhat older. Right valve, x about 5 diameters. 



Figure 4. — Tlie same, var. insculpta, portion of the surface, near the margin. > 15. 



Figure 5, 5a. — The same variety. Portions of the sculpture of the disk of a young 



specimen, x 20. 

 Figure 5b. — The same specimen. Portion of the sculpture nearer the umbo, x 40. 

 Figure 6. — Chlamys irradians. Part of hinge to show the transverse incisions (?), 



the ligament (l), the resilial pit (r), and the cardinal ribs (^), x 4. 

 Figure 7. — Chlamys glypta V. Inside of left valve, x 3 

 Figure 8. — The same. Upper part of right valve of a larger specimen; |), pectini- 



dial teeth, x 4. 

 Figure 9. — The same. Hinge of a small specimen, right valve; c, crural rib; d, 



crural denticle ; I, ligament ; i, cardinal ribs and transverse incisions ; p, pectini- 



dial teeth and byssal notch ; /•, resilial pit, x 4. 

 Figure 10. — The same. Two of the internal bicarinate radial ribs, at the margin, 



x4. 

 Figure 11. — The same. Sculpture of a large specimen close to the margin, x 8. 

 Figure 12 — Cyclopecten parvus V. and Bush. Right valve, x 8. 

 Figure 12«. — The same. Hinge of left valve, x 15. 



Figure 12&. — The same. Sculpture of the left valve near the umbo, x 100. 

 Figure 12c. — The same. Sculpture of the left valve near the margin, x 100. 



Plate XVII. 



Figure 1. — Chlamys (Flacopecten) Clintonius, young, left valve, x 8. 



Figure 2. — The same, somewhat older, right valve, x 6. 



Figure 3. — The same, slightly older, interior of right valve, x 6. 



Figure 4. — The same. Hinge of right valve of a more mature example, x 3. 



Figure 5. — The same, young. End view of posterior end of a specimen showing 



unusually large riblets. To illustrate extent of gaping and inequality of the 



valves, X 9. 

 Figure 6. — The same. A portion of the sculpture of the left valve of an unusually 



strongly sculptured example, x 15. 

 Figure "7. — The same. Portion of the sculpture from near the margin of the left 



valve of another young specimen, showing the camptonectes sculpture, x 24; 7a, 



lb, other parts of the same valve more enlarged. 

 Figure 8. — Pseudamusium simile. Left valve, x 6. 

 Figure Sa. — The same. Right valve, x 6. 



