184 S. STILLMAN BERRY. 



of masses of photogenic tissue without accessory structures 

 (intrapallial organs of Sepiolidae; proximal tentacle organs of 

 Lycoteuthis and Nematolampas; eyelid organs of Mastigoteuthis 

 glaukopis}. As a general rule they are more or less complicated. 



The principal division of the organs on morphological grounds 

 is that already noticed which places the discharging glands of 

 the Sepiolidae on the one hand, the enclosed glands of the 

 remaining photogenic genera on the other. The latter it is again 

 possible to roughly separate into three types: the no doubt rela- 

 tively primitive invaginated epithelial organs of which the 

 subocular photophores of Cranchia, Liocranchia and Leachia 

 are interesting examples, band-like expanses of photogenic tissue 

 as in Eucleoteuthis, and the spherical, ovoid or discoid organs, 

 often provided with the most extensive array of accessory mech- 

 anisms, which are found in most of the other genera. 



The organs of the last mentioned class in their highest de- 

 velopment attain to an almost unbelievable degree of complexity 

 To the primary photogenic tissue, with its invariably abundant 

 blood and nerve supply, are here added more or less efficiently 

 developed reflector mechanisms, pigment cups, lenses, diaphragms 

 directive muscles, mirrors, windows, color screens, even in some 

 cases accessory photophores, giving rise to the puzzling "double 

 organs" which are met with now and then in the most dissimilar 

 situations, so that their purpose and manner of functioning is left 

 even more than it otherwise would be a complete enigma. In 

 some cases only certain ones of these accessory structures are 

 developed, in other cases nearly all, as in the miniature search- 

 lights which yield such beautiful microscopic preparations in 

 the integument of the Abralioid and Histioteuthicl forms. 

 Space will not permit a complete description, but the presentation 

 of these various accessories in outline form will give an idea 

 their wonderful variety and serve likewise as a convenient 

 summary. The student desiring more detailed information is 

 referred to the works cited in the bibliography, particularly 

 those of Joubin ('93, '930, '936, '93*;, '94, '95, 105, 1050), Hoyle 

 (:02, 104, :09), Meyer (:o6, :o8), Vivanti (114), and the beautiful 

 memoirs of Chun (1030, :io). 



