CEPHALOPODS OF WESTERN NORTH AMERICA. 



"79 



flattened papilla, beyond which the minute conical tip is naked; its inner surface flattened, but little 

 excavated, and provided with a few (3-5) distinct transverse grooves (in all the specimens examined). 

 Suckers large at the base of the arms but rapidly diminishing in size after passing the margin of the 

 umbrella; one of the suckers on each of the lateral arms near the junction of the umbrella frequently 

 exhibits a considerable enlargement. 



Beak strong and black as usual in the genus (pi., xxxix, fig. 5). 



Color in alcohol a dark brownish gray, heavily clouded and maculated with a blackish purple. 

 On the base of the third arm, just in front of and below the e)-e on either side, is a large, distinct, round 

 oculation, usually decidedly darker in tint than the rest of the animal. In most individuals tliis spot 

 shows a dark center bounded firstly by a rather narrow dull-bluish ring, and secondly by a wider outer 

 band of the same color as the center, a feature which seems to have been obscured in the specimens 

 described by Verrill. The bluish ring has usually the appearance of being superimposed upon a uniform 

 darker area, and some examples show further a surrounding region of a lighter color. 



The young are readily to be distinguished from those of other species even when still of very insig- 

 nificant dimensions. The most important difference from the adult which they exhibit is tliat the large 

 cirri are relatively longer, seem very distinct from the other tubercles of the body, and show a strikingly 

 definite bilateral symmetry (pi. xxxiv, fig. i, 2). In addition to the postocular cirri, tlie following 

 are usually very prominent: A conical tubercle at the base of each dorsal arm, a median one on the 

 head just posterior to these, two along the median line of the body, and one large and several smaller 

 lateral ones on either side of the latter. A single longitudinal row of small dark chromatophores, larger 

 than those generally distributed over the body, may be seen on the ventral arms of extremely young 

 individuals and there are a few similar ones on the ventral surface of the body. Further it may be 

 added that tlie arms of juvenile specimens maintain with considerable constancy the relative length 

 formula 2, 3, 4, i, as given by \'errill. 



Five specimens measure as follows: 



Measurements op Polvpus bimacui-atus. 



Sex 



Author's register number. 



Total length 



Tip of body to base of dorsal arms. . . 

 Width of— 



Body 



Neck 



Head 



Length of — 



Funnel 



Dorsal arm 



Second arm 



Third arm 



Ventral arm 



Hectocotylus 



Umbrella between dorsal arms. . . 



Umbrella between ventral arms. 



mm. 

 »47o 

 102 



S8 



36 



3S 

 "385 

 "405 

 o 410 

 0360 



mm, 

 "490 



103 



St 

 34 

 34 



'33s 

 150 



"390 

 03-0 



' 178 

 SO 



109 

 138 

 llS 



134 



mm. 



" 33S 

 48 



o rso 



" 135 

 I3S 



mm. 

 6s 



7 

 3S 

 46 

 46 

 43 



o Figures only approximate. It should be remembered that in cephalopods of this type the arms are so elastic and the diffi- 

 culty of maintaining a constant degree of tension for measurement so great, that the probability of errrr is relatively very large. 

 Further, the tissues are very variously affected by the conditions of capture and preservation, but it is hoped that these measure- 

 ments will prove sufficiently true for practical purposes. 



ft Specimens mutilated. 



Type locality, San Diego, California. 



Distribution: San Pedro and vicinity, La Jolla and San Diego, California; south to San Salvador 

 (Verrill) and Panama (Verrill). 



