CEPHALOPODA OF THE HAWAIIAN ISLANDS. 307 



to be slightly the superior in size. The widely separated habitat of the two leads one to believe that 

 as both species become better known numerous other differences will undoubtedly be discovered to 

 exist between them. 



Dr. Fisher informs me that when living the animal is an object of great beauty, the sheen of its 

 delicate opalescence approaching that of mother-of-pearl. If it is so common a species in this region, 

 it seems rather remarkable that no member of the genus has been brought to light from any other part 

 of the Pacific. 



LARVAL OCTOPOD. 



There is a very curious but undetermined larval octopod in the Albatross collection from station 

 3802, 150 fathoms, between the Erben Bank and Kaiwi Channel [S. S. B. 386]. 



Suborder DECAPOD A Leach 18 17. 



Sephinia Rafinesque 1815, p. 139 (fide Binney and Tryon. p. rj). 



Decapoda Leach 1817 (fide Gray). 



Decacera de Blainville 1824 (fide Verrill). 



Decacera de Blainville 1825, p. 366. 



Decapoda d'Orbigny 1845, p. 236. 



Decapoda Gray 1847. p. 20s. 



Sephinia Gray 1849. p. 2. 35. 



Decapoda H. and A. Adams 1853, vol. 1, p. 25. 



Decapoda Keferstein 1866. p. 1438. 



Decacera Verrill 1881, p. 426. 



Arms normally 10 in number; the fourth pair originating in special pouches into which they may be 

 more or less completely retractile, and greatly modified to function as highly specialized prehensile 

 organs. Suckers distinctly pedunculate; their apertures equipped with horny or chitinous rings, which 

 may be perfectly smooth, more or less dentate, or with the upper margin greatly enlarged and produced 

 into a long incurved hook. Body short to elongate, rounded or pointed posteriorly, and always with 

 well developed terminal or lateral fins. Head and mantle sometimes continuous in the nuchal region, 

 but more often free and with a cartilaginous articulation. Gladius calcareous or horny; rarely absent; 

 in one genus (Spirula) there is an internal coiled and chambered shell. Wherever hectocotylization 

 occurs one or both of either the dorsal or ventral arms undergo the modification. 



Highly specialized photogenic organs of many types are of frequent occurrence. 



Division MYOPSIDA (d'Orbigny 1845). 



Decapoda Myopsida? d'Orbigny 1845, p. 237. 

 Myopsida Keferstein 1866, p. 1441. 

 Myopsidoz Verrill iSSr, p. 432. 

 Myopsida Hoyle 1886, p. 16, no. 

 Myopsida Pfeffer 1908, p. 15, 24. 



Eyes almost invariably covered by a continuous imperforate membrane or foldlike lid. Horny 

 rings of suckers either smooth or dentate, but never falciform. 



There are also numerous important visceral characters such as the symmetrically bipartite liver, 

 genital artery springing directly from the heart, etc. 



Family LOLIGINID£ (d'Orbigny 1845 em.). 



Loligidas d'Orbigny 1845, p. 318. 



Loligid<e Gray 1849, p. 36, 66. 



Loliginida; H. and A. Adams 1S53, vol. 1, p. 35. 



Loliginida Verrill 1SS1, p. 433. 



Lotiginidts Pfeffer 1908, p. 24. 



Loliginidce Naef 1912, p. 243; 1912a, p. 741. 



Body elongated and eylindric or cylindro-conical. Mantle free from head in the nuchal region but 

 with a cartilaginous articulation. Eyes without lid-folds, the lens uninterruptedly covered by the 

 outer skin. Fins rhombic to sagittate and terminal, or nearly as long as the mantle and marginal; more 



