23 



APPENDIX I. 



SCHEDULE OF THE LIVING CEPHALOPODA. 



Description op the Class. 



Animal possessing a shell either internal (in this case naked) or 

 external. Upper part of Body, when naked, attached to and inserted in 

 a bag-like fleshy covering (mantle, sac) which is externally cylindrical, 

 conical or oval, produced upwards at its highest portion, so as to form 

 a collar about the base of the head ; upper part of mantle sometimes in 

 actual contact with the base of the head by means of a band (la bride 

 cervicale, as in the Octopoda), sometimes not in contact, but retained in place 

 by muscular bands, and by ridges fitting into corresponding grooves 

 (Vappareil constricteur, as in most of the Decapoda). External surface 

 of mantle and head marked by pigment spots (chromophores) which 

 dilate and contract, and vary in tint through the emotions of anger, 

 fear, etc., acting on the creature. Body generally marked by openings 

 (aquiferous pores) leading into recesses of greater or less depth in the 

 head, base of arms, and near the mouth and eyes. Fins, when present, 

 lateral or terminal, rounded or angular. Ink-bag generally present. 

 Head crowned with eight (as in the Octopoda) or ten (as in the Decapoda) 

 slender prolongations of the body (arms and tentacles) of unequal length ; 

 the tentacles, two in number, occurring in the Decapoda, always much 

 longer than the arms and usually expanded at their termination (tentacular 

 clubs). Arms and Tentacles provided with cup-like suckers (acetabula), 

 which are sometimes strengthened by a horny margin, sometimes dentated 

 at their edges, sometimes on a stem, and sometimes furnished with a 

 central hook or claw. Suckers arranged in a single line, or in a series of 

 two or four, or six or eight rows, or without order. Mouth in the centre 

 of the arms, circular with a muscular lip, and a tongue armed with 

 recurved spines. Jaws with a horny parrot-like beak. Eyes large, pro- 

 jecting, sometimes provided with eye-lids, sometimes raised on promi- 

 nences. Gills (branchiae) internal, plume-like, sometimes two (as in 

 the Dibranchiata), sometimes four (as in the Tetrabranchiata). A funnel 

 shaped tube (infundibidum or siphon) sometimes valved, placed on the 

 under (ventral) side of the body, serving to eject the water used in 

 respiration, and to produce a rapid backward motion of the creature by 

 the reaction on the surrounding fluid. Shell generally internal and 

 straight, lance-like in form, with or without a stem, either rudimentary 

 or absent (as in the Octopoda), or cartilaginous (as in the Squids), or 

 cellular as in the Cuttles ; sometimes external and curved, with the turns 



