180 A. JE. Verrill — JVorth Americmi Cephalopods. 



to the parts most useful to preserve when, as will usually happen, the 

 whole cannot be saved. The measui'ements of the soft external parts 

 of CejDhalopods 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 

 'chib' 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 intei-nal ' 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 alcohol 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; tlie short arms, with their siickers ; 

 of these the left arm of the lower, or ventral, pair will probably be the 

 most valuable, being probably the one that will show the sexual dis- 

 tinction, by the alteration of its suckers toward the tip or in some other 

 part ; the latei'al 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 a)id 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. 



