71 



KNOWLEDGE. 



[April 2, 1900. 



stricted to tbe Amphij^oda, as no doubt it already was 

 in the intention of Fabricius himself. Lepekhin in 

 the following year called a Cumacean species Oniscus 

 scorpioides, recognizing by the sj^ecific name the like- 

 ness to a scorpion, but using a generic name now re- 

 stricted to some of the terrestrial Isojjoda, known as 

 woodlice, and bearing little resemblance to the tribe 

 under discussion, wliich, but for the " relict " fauna 

 of the Caspian, might be called exclusively marine. 



The segmentation of the body and the number, suc- 

 cession, and character of its appendages jsrove ths 

 Cumacea to be a true Malacostracan order. Tli 3 

 carapace overarches the appendages as far as the third 

 maxillipeds, usually leaving exposed five pairs of trunk- 

 legs, so that in this respect the Cumacea are inter- 

 mediate between the higher forms (Brachyura and 

 Macrura), in which all these limbs are as a rule covered 

 by the carajsace, and the lower (Isopoda and Amphi- 

 poda), in which not five but seven pairs of limbs are lefc 

 exposed The integument is almost always firmly crus- 

 taceous. which excites surprise, because generally such 

 obduracy of covering is met with not in puny forms but 

 in those of considerable size, and not always in them. 

 On the other hand, no surprise bubbles ujs at the ob- 

 sei-vation that these creatures have no head, that is, 

 no head sejjarated from the thorax, because the astonish- 

 ing thing would be to meet with a crab or a cumacean 

 or a crustacean of any kind possessing a well-turned neck, 

 except as an anomaly or an abnormality. All the same, 

 our first English observer. Colonel Montagu, good 

 naturalist as he was, let himself be deceived into think- 

 ing that in his specimen " the head or fore part was 

 wanting. ' He had some excuse, since this novel object 

 was only a quarter of an inch long, nor could he find in 

 it either eyes or antenuje. He named it Cancer scor- 



FlG. 2. — Psemlocniiia campi/Icispuiilea Sars. Caspiau Se:i. 

 From t-ars. 



pic)idts, thus independently in a second species recog- 

 nizing the likeness to a scorpion, while absurdly placing 

 i t in the genus Cancer as if it were a little crab — hoping 

 perhaps with a mop to stem the tide of progress which 

 has been persistently comminuting the original genus 

 Cancer, an amorphous lump, into scores and hundreds 

 of more or less shapely genera. 



Montagu could find no eyes in his small specimen. 

 The explanation of this may be that the small median 

 eye with its eight lenses had been accidentally obscured. 

 In the Cumacea, as in other orders of crustaceans, there 

 are species which see and there are sightless species. It 

 •will be remembered also that the Malacostraca are divided 

 into two great groups, the Stalk-eyed and the Sessile- 

 eyed. The strange thing is that for a great many years 

 the scientific world could not come to an agreement on 

 the knotty point, whether the Cumacea belonged to the 

 former group or to the latter. If they had no eyes at 



all, well and good, there was no need to argue about the 

 stalks. But successive writers, Lepekhin, Milne-Edwards, 

 Goodsir, affirmed that they had eyes, and Say, thouga 

 he could not see them, took their presence for granted. 

 Kroyer began by examining species that were really 

 blind. About the same time Goodsir investigated species 

 that really had eyes. Then Erichson, in 1844, expressed 

 what he supposed to be Goodsir's opinion by saying, 

 '■ the stalked ej-es are very small and concealed under 

 the carapace (which no doubt was the cause of Kroyer 's 



Fig. 3. — Cumella limicola Sars. E_ve> aud front of Carapace. 

 From Sars. 



no*- finding them)." Kroyer, for his part, in 1846, be- 

 lieved the eyes to be what one might call an ocular 

 delusion; and so he says, " Goodsir thought that there 

 must be eyes to be found in the creature and he therefore 

 found them." Goodsir unhapi^ily perished in an Arctic 

 expedition, and was never able to defend or explain his 

 clearly printed statement that " the eyes in this tribe 

 are exceedingly small, they are pedunculated, but 

 sessile.'' It is amusing to notice how this remark has 

 been treated by subsequent writers. Erichson and 

 De Kay accept the epithet " pedunculated " and ignore 

 the qualifying words " but sessile, " which seem to come 

 from the lips of Mr. Facing-both-ways. Kroyer and 

 Bell cannot av/ay with a description which is, as they 

 rightly say, a contradiction in terms. But, look you, in 

 spite of this, in 1870, Anton Dolirn found or fancied in 

 a larval form a little downward bent eyestalk, which 

 at a later stage was completel)' enclosed by the carapace. 

 This he offers as an olive branch, a symbol of peace, be- 

 tween the disputants, saying. " Curiously both sides are 

 right, — as already before me Henry Goodsir expressed 

 it, ' the eyes are pedunculated, but sessile. " He seems 

 to forget that Goodsir was concerned not with immature 

 but with full-grown forms. With a boldness greater 

 than Dohrn's, Eugene Hesse, in 1868, described an adult 

 cumacean as having eyes which " are not precisely 

 sessile, nor yet completely pedunculated ; they hold 

 the mean between the one thing and the other." What 

 could be more accommodating, what more pacificatory ■ 

 And, after all, the whole controversy hangs on a mis- 

 pi-int, as suggested by Fritz Muller in 1865. Nothing, 

 I think, in this uncertain world can be more absolutely 

 certain than that Goodsirs intention was to say that 

 the eyes are " not pedunculated, but sessile," in accord- 

 ance with the obvious fact. Only, the printer or the 

 penman left out the inconsiderable word "not." 

 Goodsir goes on to say of the eyes that " they are placed 

 very close together," and that " they are covered by the 

 shell," arrangements not absolutely incompatible with 

 the possession of stalks, though alien to it, but the 

 plates which accompany his description exhibit sessile- 

 eyed species with the most uncompromising plainness. 

 No man in his senses would describe a new scientific 

 object as " long, but short," or " black, but white, " 

 without some explanatory signal that he was indulging 

 in a whimsical paradox. 



