ZOOLOGY. 603 



by transparent skin and lidless, arms of the fourth pair hectocotjiized, 

 and with an internal chambered shell or phragmacone. 



This superfamily includes only one living family, but the extinct 

 Belemnitids, Belopterids, and Belosepiids ha^'e been associated with it 

 as constituents of a natural superfamily group. 



9. SpiruUds. — Spiruloid Decaceres with the internal shell or phrag- 

 macone, an elongated chambered cone, wound in a loose coil of several 

 whorls. 



This family is only represented, so far as known in the existing fauna, 

 by the genus Spirula, whose shell is so well known to all collectors, but 

 Professor Steenstrup has associated in the same family with it a genus 

 named Idiosepius. Idiosepius is destitute of a shell, but has a tendinous 

 support which is regarded as the homologue of the shell, as well as the 

 gladius of Loligo. 



F. Sepioloidea. — Decaceres with eyes covered by a transparent skin, 

 but with false eyelids more or less free, arms of the first pair hectocotyl- 

 ized, and with the gladius corneous and rudimentary, or absent. 



. 10. Sepiolids. — The only known sepioloid decaceres. 



The families of Octopod Dihranchiates. 



The octopods in late years have been generally segregated into two 

 principal groups, (1) the pelagic, including the Argonautids and Philo- 

 nexids, and (2) the littoral, embracing the Octopodids and Cirrhoteuthids. 

 But M. Fischer has proposed to differentiate them into two groups, dis- 

 tinguished by the development of one or more rows of suckers, the 

 "Cirrhoteuthidse" and "Eledonidae" having one row("monocotylea"), 

 and the Octopodidae, Tremoctopodidse (Philonexids), and Argonautidae 

 having two or three ("polycotylea"). Professor Verrill has made known 

 a "new" family (Alloposidae), and admits the following: 



Argonautids. — Octopods with an ovoid flnless body, the two upper- 

 most arms (in female) expanded terminally into broad flattish vela- 

 menta which secrete a papery spiral single-chambered involute nautili- 

 form shell. 



The family is specialized by the development of a shell, which serves 

 as an ovicapsule in the female. The male is very much smaller. 



Philonexids or Tremoctopodids. — Octopods with ovoid finless body, 

 tapering arms moderately connected by membrane, and "edge of man- 

 tle united to the base of the siphon laterally by a button-like cartilage 

 fitting in a corresponding pit on the inner surface of the mantle." 



Alloposids. — Octopods with ovoid finless body, tapering arms con- 

 nected by a moderate web, and mantle "united directly to the head, not 

 only by a large dorsal commissure, but also by a median ventral and 

 two lateral longitudinal commissures, which run from its inner surface 

 to the basal parts" of the siphon." 



This family has been constituted by Professor Verrill for a single 

 species {AUoposus mollis) discovered by Lieutenant Tanner, under the 



