ZOOLOGY. 601 



It will be thus seen that the growth of the shell, whether in a spiral 

 or other curve or even straight, is not only subordinated to other char- 

 acters (and undoubtedly with propriety), but is ignored as a family 

 character. 



The families of Decacerons Dibranchiates. 



The suborder of Decacerous or Decapod Cephalopods has been gen- 

 erally differentiated into two primary groups — (1) the "Oigopsidae," re- 

 puted to have the "eyes naked in front, furnished with free lids, with or 

 without an anterior sinus ; pupils circular," and (2) the " Myopsidae," 

 contradistinguished by "eyes covered by transparent skin, sometimes 

 with a thickened fold, forming a lower lid, pupils crescent-shaped." 

 It has been doubted, however, whether undue value has not been at- 

 tached to such distinctions, although their importance, to a greater or 

 less extent, has been admitted. During the past year several modifica- 

 tions have been proposed. 



Mr. Tryon divided the Decaceres into (a) Decapoda chondrophora 

 and (6) Decapoda calcifera. 



Professor Steenstrup adopts the groups Oigopsidae and Myopsidae, 

 and attaches importance next to the particular arm of the male which 

 is hectocotylized. He recognizes two series of Myopsids, which he calls 

 "families," viz, (1) the "family of Rossia-Sepiola = Sepiolini," of which 

 an arm of the first part is hectocotylized, and (2) the "family of Sepio- 

 Loligini," whereof the arm of the fourth pair is hectocotylized ; the lat- 

 ter is subdivided into the groups (a) Loliginei, (6) Eusepii, (c) Sepiadarii, 

 and (d) Idiosepii. 



Dr. Fischer attaches primary importance to the nature of the internal 

 dorsal support or skeleton dividing the suborder into (1) Chondrophora, 

 (2) Sepiophora, and (3) Phragmophora. The Chondrophora are subdi- 

 vided into the "sections" Oigopsidae and Myopsidae. 



Professor Verrill admits the groups of d'Orbigny, but adds that they 

 are, "perhaps, more convenient than natural," and he subdivides the(l) 

 Oigopsidae into two superfamilies, the Teuthidea and Taouidea, and the 

 (2) Myopsidae into two also, the Sepidea and the Sepiolidea, but sug- 

 gests that the Spirulidae (provisionally referred to the Sepidea) "might, 

 perhaps, be best placed with several fossil forms in a division of which 

 it is the sole surviving genus." 



The extent to which the several characters referred to coincide or 

 traverse each other may be appreciated from the diagnoses of the sev- 

 eral families, which have been chiefly condensed from Professor Verrill's 

 catalogue, etc. 



A. Teuthidoidea. — Decaceres with eyes naked in front, with free 

 lids, and not protuberant ; with a subterminal valve to siphon, and with 

 the mantle attached to the siphon by free connective cartilages. 



1. Onychoteuthids.—Tenihidoid Decaceres with free arms, with lachry- 

 mal sinuses; siphou valviferous, well developed nuchal crests, and ten- 



