Apbil 2, 1900.] 



KNOWLEDGE. 



lo 



Xot the eyes alone excited eontroversy. A question 

 was raised whether these peculiar little animals wero 

 iinything more than larval forms and, what is almost 

 more peculiai- than the animals themselves is, that th-; 

 justly illustrious Henri Milne-Edwards, down at least 

 to 1S64, was still on the wrong side of the argument. 

 Though he had himself with some care introduced a 

 Cumacean to European science in 182S, though hii 

 attention was repeatedly called to the subject, though 

 he had the writings of Goodsir, Kioyer, and Spenc;^ 

 Bate, conclusively showing the right view, he remained 

 obdurate. With him was L. Agassiz, with him 

 apparently, though in less demonstrative fashion, 

 were Dana and Huxley. They all agreed in sup- 

 posing the Cumacea to be immature forms, and they 

 were all wrong. In fact the Cumacean at birth al- 

 ready resembles its mother, except that the last pair 

 of trunk-legs is as yet undeveloped. A natural warn- 

 ing against the larval hypothesis lay also in the 

 strong sexual dimorphism of these animals. The males 

 are distinguished from the females by the great length 

 to which their second antenna; arc developed, by having 

 exopods or swimming-branches attached to all the firsc 

 four pairs of trunk-legs, and having plcopods on th? 

 Prst five, or some of the first five, segments of the pleon 

 Not often are all these distinctions available together, 

 but always one or more of them. The superior swim- 

 ming power of the male makes him often at night t•im^.' 

 a victim to the tow-uet sweeping the surface of the sea, 

 while his less agile mate is lying in safety far below. 



Some of the species show an almost balloon-like expan- 

 sion of the front part. But, be it corpulent or slim, 

 its contents are much the same, and worthy of investi- 

 gation. For this, however, they present a task of some 

 delicacy, being soft and easily damaged goods packed m 

 and attached to a rather unyielding and brittle case. 

 This lielps to account for the strange muddle which 

 P. J. van Beneden made in 1861, for, while examining 

 different species, he seems to have lost two pairs of 



Fig. 4. — Cyclaipoides ferox (Fisclicr). Bay of Biscay ami 

 Mediterranean. From .Sars. 



the appendages and not to have definitely known 

 which two pairs he had lost. At the same time, 

 by the general excellence of his work, he created a confi- 

 dence which misled Claus into believing that in^ thi 

 Cumacea two pairs were really missing. That is not the 

 fact. Everything is in order. Those who dissect with 

 the needful skill will find in the Cumacean a heart and 

 " liver,' ovarial or seminal ducts, intestinal canal, gang- 

 lionic nerve-chain, thinly partitioned branchial cham- 

 bers, eyes (or no eyes), two pairs of antennae, mandibles, 

 two pairs of maxillae, three _ of maxillipeds, and com- 

 monly five pairs of trunk-legs. Of all these the su- 

 premely interesting objects are the first maxillipeds. 

 These somewhat leg-like jaws have in their standard 

 features nothing to call for special remark here. The 

 accessories are the essentials. Every Malacostracan 

 appendage, as the reader knows, may possess an epipod 

 on the first and an exopod on the second joint, but 

 these are often inconsiderable, evanescent, or wholly 

 wanting. In these Cumaicean maxillipeds they are large 

 and of the first importance, coalesced into a powerful 



organ, stretching backward, stretching iui„,,i,i. <i, ..'s- 

 sential to the life of the Cumacean as they nre in some 

 respects unique in Malacostracan structure. The hinder 

 part forms a great branchial lamina, commonly ampli- 

 fied by numorows leaflets or vesicles on its surface. 

 The forepart ends in a pellucid nienibiauo. iii .some 



FlO. .5.— One maxilliped of Fxo. 0. — Maxillic and first maxiUipeds 

 first pair of Diasti/Us of Dia-i/i/lis sciilpla Sars. From 



scujpla, in lateral view. Sars. 



species, when the animal, alive, and lying still, is viewej 

 in sea water, the pair of pellucid ends will be seen lo 

 shoot forward at the front, and then to be in turn 

 withdrawn. When advanced, they form, with the 

 frontal projection of the carapace, a closed but yielding 

 tube through which the water of respiration is ex- 

 pelled. When retracted, they fold over to preclude the 

 return of the used-up water, while the maxillae make 

 way for a fresh stream to bathe the branchial blade. 

 This apparatus is not constructed precisely in the sanu 

 way in all the families of the group, and, though th ; 

 most singular part of the organism both in stnicturc 

 and mode of action, it is not the only part worthy of 

 notice. But space is less at our command than speci- 

 mens are at the command of the student. To them 

 above all he should have recourse, as well as to the 

 copious literature by which this subject is now illumina- 

 ted. Among the more recent writers, A. M. Norman, 

 H. J. Hansen and Jules Bonnier arc conspicuous, but 

 all the pens and pencils of all the authors on this sub- 

 ject have not produced enough to equal what has been 

 done by G. O. Sars. As for specimens to examine, thi 

 sands of the shore, the dcptlis of the sea and its sur- 

 face, are now known to yield these creatures in abund 

 ancc, so that there is no longer need to wonder and 

 blunder over solitary examples, though the need for 

 seeing eyes and open minds, for caution and for cour- 

 age, remains the same ;is of old. 



