EXPLANATION OF PLATES. 



Plate I. 



Figs. 1-5. ScalpeUum si-roemii Sars. Series of a form from St. Peter's Bank, showing 

 changes with age. Cat. No. 21547, U.S.N.M. 

 6, 7. ScalpeUum stroemli Sars. Typical Norwegian specimen in side and ven- 

 tral views. 

 8, 9, 10. Scalpelhun strocmii suhstroemii, new subspecies, Albatross Station No. 2693. 

 11, 12. ScalpeUum stroemii latirostrum, new subspecies. Type, Cat. No. 10780, 



U.S.N.M., Albatross Station No. 2527. 

 18, 14. Scalpellnm stroemd latirostrum, new subspecies. Cat. No. 10752, U.S.N.M., 



Albatross, 1885. 

 15, 16. ScalpeUum stroemii latirostrum, form having some features of substroemii. 

 Cat. No. 9020, U.S.N.M. 



Plate II. 



Fig. 1. Scalpelhun giganteum Gruvel. Side view of specimen largely denuded of 

 the cuticle, from Albatross Station 2658. Natural size. 

 2, 3. ScalpeUum regium latklorsum, new subspecies, dorsal and lateral views of 

 type. Natural size. 

 4. ScalpeUum regina, new species. Diagrammatic section of carina. 

 5, 6. ScalpeUum regina, new species. Detail of base of carina, and lateral view 

 of type. Natural size. 



7. ScalpeUum regium latidorsum, new subspecies. Section of carina, diagram- 



matic. 



8. Scalpellnm regium Wyville Thouison. Section of carina, diagrammatic. 

 9, 10. ScalpeUum regium, variety from Station 3342 in the Pacific. Dorsal and 



lateral views. Natural size. 



Plate III. 



Fig. 1. Scalpellu7n giganteum Gruvel. Side view of an old specimen showing 

 sutural lines between the imperfectly calcified i)lates. Natural size. 



2. Scalp)ellum velutinum Hoek. Group of ten individuals. Cat. No. 12480. 



Natural size. 



3. Scalpelltmi velutinum Hoek. Group, showing adult and young individuals 



in carinal aspect. Natural size. 

 4, 5. ScalpeUum regium Wyville Thomson. Cat. No. 8629, U.S.N.M. 



Plate IV. 



Figs. 1-5. ScalpeUum stearnsii Pilsl)ry. 1, first cirrus; 2, terminal appendage; 3, seg- 

 mentfrom middle of sixtli cirrus, anterior side toward the left; 4, mandi- 

 ible; 5, maxilla. 

 6-8. ScalpeUum regium Wyville Thomson. 6, mandible; 7, lower point of same, 

 much enlarged; 8, terminal appendage. 



9. ScalpeUum aurivUlii, new species. An intermediate segment of the sixth 



cirrus, anterior side on the right. 

 10-12. ScalpeUum regium, variety from Albatross Station, 3342. 10, first cirrus; 

 11, maxilla; 12, mandible. 



13. ScalpeUum auriviUu. Terminal appendage. 



14. ScalpeUum regium, var. from Station 3342. Terminal appendage. 



15-18. ScalpeUum imperfectum, new species. 15, intermediate segment from sixth 

 cirrus; 16, terminal appendage; 17, mandible; 18, lower tooth and 

 lower point of same, more enlarged. 



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