92 U.S. NATIONAL MUSEUM BULLETIN 291 



conus (usually long) formed by the ventral infolding and fusion of 

 the lateral edges of the vane. Diverse families with this type of gladius 

 include the Chiroteuthidae, Mastigoteuthidae, Joubiniteuthidae, Bato- 

 teuthidae, Grimalditeuthidae, Brachioteuthidae, some Cranchiidae, 

 etc. Another type of gladius, like that of the Ommastrephidae, is 

 heavily constructed with a thick rhachis, a long, narrow (or absent) 

 vane, and a short, heavy conus. Lycoteuthids, enoploteuthids, and 

 histioteuthids have a type of gladius tliat tends to have a short free 

 rhachis, a fairly broad, convex or hourglass-shaped vane, and an open 

 conus. The Onychoteuthidae have a short, free rhachis, a long, narrow^ 

 vane, and a long spikelike extension of the conus. The paddle-shaped 

 bathyteuthid gladius, with its long, free rhachis, broad, thin vane, 

 and flat, open "conus," is unmatched in simplicity of shape and struc- 

 ture; at the present stage of knowledge about teuthoid gladii, the 

 bathyteuthid gladius cannot be closely associated with tlie pen of 

 any other family. 



One of the most distinctive features of the Bathyteuthidae is the 

 occurrence of suckers on the buccal lappets. This feature alone sets it 

 apart from all other oegopsid families except the Ctenopterygidae. 

 Ctenoyteryx^ of course, was included in the Batliyteuthidae for many 

 years as a subfamily, primarily because of tliis shared character. In 

 addition, Ctenopteryx has supposed accessory nidamental glands, a 

 unique organ in the Oegopsida. Some sepioids and myopsids have 

 buccal suckers and accessory nidamentals also, and Naef regarded 

 them as primitive characters. 



The occurrence of the accessory nidamental glands in Ctetiopteryx 

 in conjunction wath the presumed primitiveness of the buccal suckere, 

 four rows of arm suckers, and more than four rows of club suckers, led 

 Naef to place the Bathyteuthidae at the beginning of the Oegopsida 

 next to the Myopsida. 



The question is not settled, however, for it may be argued that some 

 of these characters are not primitive but are adaptive. Many rows of 

 suckers on the arms and clubs and suckers on the buccal lappets may 

 be adaptations to particular environmental requirements or, more 

 specifically, to certain types of food organisms. The many-rowed condi- 

 tion, or tendencies toward it, occurs in several diverse groups of oegop- 

 sids: on the arms of gonatids, joubiniteuthids, enoploteuthids, and 

 octopoteuthids, and on the clubs of mastigoteuthids, promachoteuthids, 

 joubiniteuthids, gonatids, histioteuthids, bracliioteuthids, and bato- 

 teuthids. All of these groups are mesopelagic or bathypelagic or, 

 in the case of gonatids and bracliioteuthids, they are transitional forms 

 that live closer to the surface and range dow^n into the mesopelagic 

 zone. An increased number of suckers on arms and tentacles would be 



