138 



KNOWLEDGE, 



[.Tuns, 1902. 



whiitevor olsc may be or not be the a])|)UrtcnaiiO('s of a 

 head, it always includes the mouth. A lioad without a 

 mouth is worse oft" than a duke without a duehy. So far 

 then the proboscis above described liy haviiij,' a mouth 

 makes a capital claim to bo the hcail, and when it hajipens 

 to be fusiform, its neck-like altaclniu'iit to the rest of the 

 body fjives if a semblance of beini^' not merely a ]iart of 

 the head but the whole. Many animals, crustaceans and 

 sjjiders for example, dispense with a neck, having; the head 

 fused with the trunk. But it is not easy to think of an 

 animal which has a neck in the middle of its head, enabling 

 it to double one half under the other. This singular 

 acrobatic performance is, however, accomjilished in the 



Eurycyde hispida (Kroyer) ; ambulatory legs omitted. From Sars. 



present group, as for instance by Eurycyde his'pida 

 (Krover) ; but it needs some explanation. For arthropods 

 in general, and for vertebrates it must be admitted that, 

 besides the feeding aperture, two other constituents of 

 supreme importance, the eye and the brain, are always 

 localized in the head. The eyes and brain do not wander 

 away from the head of an arthropod, unless they wander 

 away from the animal altogether. Yet look now at these 

 perverse Pycnogonida. Behind the proboscis, which is 

 sometimes relatively huge, there is a body consisting of 

 four segments, followed by a little trivial abdomen, articu- 

 lated or in coalescence, depressed, outstanding, or more 

 frequently upturned. The four segments of the trunk are 

 often very distinctly separated one from the other, but in 

 some species they are more or less fused together, although 

 the original independence of the last three is always suffi- 

 ciently guaranteed by the ])air of legs which each has iu 

 attachment to its sides. The first segment also has a 

 similar pair of legs in similar lateral attachment, but it 

 has much more. It is capable of liearing three other pairs 

 of appendages, and sometimes, though not always, exercises 

 this capacity. The nervous mass that does duty for a 

 brain is lodged within it. On its outside rises an eminence, 

 a little watch-tower, normally beset with four simple eyes, 

 two of which look backward and two forward. That this 

 first segment, then, to judge by the four pairs of appen- 

 dages, is in reality composite, few zoologists will be inclined 

 to dispute. That part of it is ceishalic or in the nature of 

 a head-piece, since eyes and brain are lodged in it, most 

 will readily itdmit. But this admission carries with it the 

 inference that the proboscis, notwithstanding its possession 

 of the buccal orifice, is not properly or exclusively the 

 head. It may rather be regarded as the throat and mouth 

 projected strongly forward so as to assume an abnormal 

 prominence. It is in keej)ing with the eccentric character 



of these creatures, the " nobodies " of our title, that they 

 should thus threaten immense gulosity in spite of those 

 circumstances which convict them of hermit-like abste- 

 miousness. 



The three pairs of appendages that precede the walking 

 legs on the composite first segment appeal for distinctive 

 names, and still remain in the distressful condition of not 

 knowing with any sort of certainty what to call themselves. 

 Of the first pair it may be said that they are normally 

 three-jointed and chelate. They frequently extend Ijeyond 

 the proboscis in a way that would seem convenient for 

 offering meat to its mouth. But they display many 

 vagaries. Very occasionally they are four- jointed, sonn'- 

 times they are two-jointed or one-jointed, or no-jointed, 

 disappearing altogether. Under some of these conditions 

 they cease to be chelate, not being able to form pincers 

 with fewer joints than two, or not choosing to do it with 

 that number or more. At times they remain chelate. 



7"\..Jl# 



JSlymphon purliicidum, lloek. Front of liody from below. 

 From Hoek. 



though not reaching so fair as the month-opening. It 

 must be tantalizing to the mouth if they persist in oflering 

 food from an unattainable distance. But perhaps they 

 adopt the policy of the long spoon, presenting a desirable 

 morsel on the end of a stalk. In contrast with the incon- 

 stancy and variability of these appendages in the adult, 

 they are found to be iu the larva, so far as is known, 



