no. 1826. M0LLU8KX OF THE GENUS BITTIUM— BARTSCH. 413 



The type (Cat. No. 126774, U.S.N.M.) comes from the Gulf of 

 California. It has lost the nucleus. The eight remaining turns 

 measure: Length 6.1 mm., diameter 2.1 mm. 



EXPLANATION OF PLATES. 



All of the figures are enlarged about eight times. The measurement cited after each 

 species is the actual length of the specimen. 



Plate 51. 



Fig. 1. Bitlium (Lirobittium) catalinense; type; 7.5 mm.; p. 402. 



2. Bittium (Lirobittium) interfossa; type; 6.2 mm.; p. 401. 



3. Bittium (Lirobittium) catalinense inornatum; type; 7.2 mm.; p. 403. 



4. Bittium (subgenus?) fetellum; type; 9.3 mm.; p. 409. 



5. Bittium (subgenus?) oldroydse.; type; 13.3 mm.; p. 408. 



6. Bittium (Lirobittium) interfossa; 8.3 mm.; p. 401. 



Plate 52. 



Fig. 1. Bittium (Semibittium) purpureum ; Cat. No. 56004, U.S.N.M.; p. 391. 



2. Bittium (subgenus?) decussatum; type; 4 mm.; p. 409. 



3. Bittium (Semibittium) purpureum; cotype; 7.3 mm.; p. 391. 



4. Bittium (Lirobittium) ornatissimum; type; 12.1 mm.; p. 403. 



5. Bittium (Lirobittium) ornatissimum; 9.2 mm.; p. 403. 



6. Bittium (Semibittium) armillatum; type; 9.5 mm.; p. 391. 



Plate 53. 



Fig. 1. Bittium (Lirobittium) munitum; cotype; 7.8 mm.; p. 404. 



2. Bittium (Lirobittium) munitum; cotype; 7 mm.; p. 404. 



3. Bittium (Semibittium) vancouverense; cotype; 7.8 mm.; p. 392. 



4. Bittium (Lirobittium) munitum munitoide; type; 8.2 mm.; p. 405. 



5. Bittium (Bittium) panamense; type; 14 mm.; p. 3S6. 



6. Bittium (Bittium) johnstonse; type; 7.9 mm.; p. 387. 



Plate 54. 



Fig. 1. Bittium (Semibittium) attenuatum; cotype; 8.8 mm.; p. 393. 



2. Bittium (Semibittium) attenuatum (type of B. esuriens).; p. 393. 



3. Bittium (Semibittium) attenuatum multijilosum; type; 9.2 mm.; p. 395. 



4. Bittium (Semibittium) attenuatum boreale; type; 10.1 mm.; p. 395. 



5. Bittium (Semibittium) attenuatum; cotype; 10.2 mm.; p. 393. 



6. Bittium (Semibittium) attenuatum latijilosum; type; 10 mm.; p. 395. 



Plate 55. 



Fig. 1. Bittium (Lirobittium) cerralvoense; type; 7.9 mm.; p. 406. 



2. Bittium (subgenus?) giganteum; type; 18.8 mm.; p. 410. 



3. Bittium (subgenus?) casmaliense; type; 18 mm.; p. 411. 



Plate 56. 



Fig. 1. Bittium (subgenus?) arnoldi; type; 16.8 mm.; p. 411. 



2. Bittium (Lirobittium) asperum lomaense; type; 7.1 mm.; p. 406. 



3. Bittium (Lirobittium) asperum; 8.3 mm.; p. 405. 



4. Bittium (Semibittium) rugatum; type; 12 mm.; p. 397. 



5. Bittium (Semibittium) rugatum; 10 mm.; p. 397. 



