98 CATALOGUE OF CEFHAXOPODA. 



ff I Apex very blunt, and produced. S. tuberculata, n. 6. t. 6. 

 (S. papillata, t. 3. S. mammillata, t. 4.*) 

 S. Lefebrei, n. 8. t. 24. £ 1. 6. 



** Shell ohlo?ig, produced behind. 



S. inermis, n. 20. t. 6.* (S. sinensis, n. 20.) S. ornata, 

 n. 19. t. 22. Microcheirus, n. 21. (inermis, t. 20.) 



*** Shell very narrow behind, and arched. 



■j" Apex simple. 



S. australis, n. 18. t. 12. f. 7—11. S. Rupellaria, n. 16. 



t. 13. f. 10. 13. S. capensis, n. 28. t. 7. f. 113. 

 S. Orbigniana, n. 27. f. 5. S. australis, n. 23. t. 7. f. 4. 



ff Apex dilated. 



S. elegans, n. 26. t. 8. f. 1—5. S. elongata, n. 17. t. 24. 

 f. 7—10. 



The shell of S. officinalis and S. apama have the inside of the 

 front part, which is next to the back of the animal, covered with a 

 hoodlike horny plate, apparently formed of the continuation of the 

 cartilaginous margin which has not been observed in the other 

 species. 



See Longchamps {Mem, Soc. Lin. Noi^m. v. 1835, 79.) and 

 Buckland (Bridgewater Treat, ii. t.) on the structure of the shell. 



Synopsis of the Sections of the Genus. 



§ Sessile Arms with small equal Cups, all in four regular series. 



* Tentacular Arms with five or six series of unequal- 

 sized Cups. 



** Tentacular Arms with five or six series of subequal 

 moderate-sized Cups. 



3 * Tentacular Arms with twenty series of unequal-sized 



Cups. 



4 * Tentacular Arms with eight or ten series of small equal 



Cups. 



§§ Sessile Arms with small equal Cups ; the two dorsal Arms with 

 only two rows, rest with two and four. 



§§§ Sessile Arms with unequal-sized large and small Cups. 



^^B, — ^When the animal is unknown, the species is arranged next 

 to that whose shell it most resembles. 



