180 A, BE. Verrill—North American Cephalopods. 
to the parts most useful to preserve when, as will usually happen, the 
whole cannot be saved. The measurements of the soft external parts 
of Cephalopods are, for the most part, only approximate, and they 
are not all of equal value, for some parts are more changeable in size 
and shape than others. The long, contractile tentacular-arms, espe- 
cially, are liable to great variation in length according to their state 
of contraction or extension, and therefore their relative length is of 
little or no value in discriminating species. Unfortunately this, either 
by itself or combined with the length of the ‘body’ as total length, 
is often the principal one given. The circumference of the body 
varies, likewise, according to its state of contraction or relaxation, 
and the ‘ breadth’ of the body, when such soft creatures are stranded 
on the shore, will depend much upon the extent to which it is collapsed 
and flattened from its proper cylindrical form, and is of less value than 
the circumference. Measurements of the length of the body to the 
mantle edge, and to the base of the arms; length and circumference 
of the various pairs of short arms; of the length and circumference 
of the head; size of the eyes; length and breadth of the tail-fin; 
size of the largest suckers on the different arms; and size of the 
‘club’ of the long arms, are all very useful and valuable. The 
shape of the tail-fin should be carefully noted, also the presence or 
absence of eye-lids, and of a sinus or groove at the front edge of 
eye-lids. The size and shape of the thin internal ‘bone’ or ‘pen’ is 
particularly desirable. Usually it will not be possible to preserve 
the pen in any satisfactory shape by drying, for it cracks in pieces and 
curls up. It may be preserved packed in salt, in brine, or in alcohol. 
The same is true of the beak. The horny rims of the suckers can usu- 
ally be dried, but are better by far in aleohol or brine. The parts most 
useful for preservation in alcohol or salt, in cases when only a portion 
can be saved, are the long tentacular-arms, especially their terminal 
‘clubs’ with the suckers in place; the short arms, with their suckers ; 
of these the left arm of the lower, or ventral, pair will probably be éhie 
most valuable, being prob: bly ae one that will show the sexual dis- 
tinction, by the alteration of its suckers toward the tip or in some other 
part; the lateral arms next to the ventral are next in importance; 
the caudal fin, and if possible the entire head, should be preserved ; 
‘also the ‘ pen,’ if possible. In cases where the head cannot be saved 
entire, even with the arms removed, the beak and tongue, and other 
fleshy parts in and behind the beak, should be carefully preserved, as 
nearly entire as possible, either in strong brine or alcohol. 
