REPORT OF COMMISSIONER OF FISH AND FISHERIES. [138] 
The ratio of the diameter of the largest tentacular suckers to the 
mantle-length varies, in the male, from 1:50 to 1:90, averaging about 
1:65; in the female it varies from 1:36 to 1:54, averaging about 1:45. 
The proportion of the length of the dorsal arms to the mantle-length, 
in the male, averages about 1:3.50; in the female about 1:2.75. 
The pen of the female is relatively broader and shorter than that of 
the male (see Table A). 
The best and most positive external characters for distinguishing the 
sexes are the hectocotylized condition of the left ventral arm of the 
male, near the tip (Plate XXVI, figs. 3, 3 a), and the presence, in the 
female, of a horseshoe-shaped sucker, or place for attachment of the 
spermatophores, on the inner buccal membrane, below the beak (fig. 4, 
s,) These characters, however, are not present in the very young indi- 
viduals, and in those with the mantle two or three inches long they 
appear only in a very rudimentary state.* 
A.—Sexual variations in the pen (measurements in inches). 
i 
| dP. |G 9V.|F10V.| S W.| QE. | 9 EE.| 917V.) 9 An. 
—-  —————} , 
Benet OE POlpse= ses ae eee 10.50 | 10.20 9.55 8. 50 7.75 7. 65 7.55 7.50 
Length of shaft: 42.52.52 ¢...-2.2-i¢ 1.40 2.10 | 2.20 2. 00 2. 00 1.10 1.50 1.50 
Length of blade. -- nos s 2s en = ae 9.10 8.10 7.35 6. 50 5.75 6.55 6. 05 6. 00 
Breadth of shaft ..----.-..:-.....-- - 50 | - 35 +40 - 40 15 . 38 -35 .35 
Breadth of blade:.- 22-20. sina - <a 1. 40 1.15 1. 02 - 98 1. 00 1. 35 1.25 1.30 
PROPORTIONS. 
Greatest breadth to length.-.-.... Ls 7. 50 8.86 | 9.36 8. 67 7.75 5. 66 6. 04 5. 76 
| 
The specimen marked Anis from Cape Ann, Mass. (var. borealis); that marked 2 E is var. pallida, 
from Astoria, N. Y.; the rest are from Vineyard Sound, Mass. 
The adult males have the left ventral arm conspicuously hectototy- 
lized (Plate XX VI, figs. 3, 3a) by an alteration and enlargement of 
the sucker-pedicels and a decrease in the size of the cups of the suckers, 
some of which usually disappear entirely, especially in the outer row. 
The modification commences at about the 18th to 20th sucker, by the 
swelling of the bases of the pedicels; on succeeding suckers this rapidly 
becomes more marked, and the swollen bases of the pedicels become 
more elongated and gradually become compressed transversely, while 
the size of the cups rapidly decreases till at about the 28th to 30th they 
are very minute and rest at the summits of the large, flattened, acute- 
triangular supports; from the 30th to 35th the cups usually become 
mere rudiments, or disappear in large males; beyond this the cups 
again grow larger and the pedicels decrease in size, till the small suckers 
become normal on the tip of the arm. About twenty-five to thirty of 
* Professor Steenstrup formerly advanced the opinion that the males of Octopus and 
other genera of Cephalopods were provided with the hectocotylized arm from the first, 
but this we have not found to be the case. The hectocotylized condition of the arm in 
Loligo is developed in proportion to the development of the internal sexual organs, 
and is first distinctly noticeable in the larger of the young ones taken in autumn, and 
in the spring in the young ones that have survived their first winter. 
