244 



KNOWLEDGE 



[NOVEMBEB 1, 1898. 



JJomanoHcola insolens. from A. Scott. 



the sphere of its activity is so limited." Another, I which 

 is at home with the horse mussel, is said to have both body 

 and ovisacs coloured of a brilliant red, thus pleasingly 

 harmonizing with the orange-coloured body of its red- 

 footed host, like a polite lady choosing her costume to 

 match the furniture of a friend. A species described by 

 Messrs. T. and A. Scott as residing in a nudibranch mollusc 

 is branded by them with the specific name of insolens.. It 

 certainly takes liberties with its host far beyond those 



which the 

 commensal and 

 semi -parasitic 

 forms allow 

 themselves. In 

 this case the 

 authors tell us 

 that they found 

 the parasite 

 ' ' entirely 

 buried in the 

 body of the 

 mollusc, with 

 the exception of 

 the last abdo- 

 minal segment 

 and the ovi- 

 sacs." Even 

 when it was dug 

 out,noantennii> 

 or mou th - 

 organs could be 

 discerned. The 

 clasping organs 

 of the embedded trunk are shown by the figure to be of a 

 quite unexceptionable tenacity, as little likely to let go 

 when once fixed as the teeth of any bulldog. Echinoderms, 

 annelids, sea-feathers and various other zoophytes, give 

 lodgings to the Copi'poda. The latter also readily take up 

 with other crustaceans, not on any terms of friendship, but 

 merely to suit their own convenience. One species lives 

 with a hermit crab, and is difficult to capture from the 

 wiliness with which it conceals itself within or underneath 

 the shell occupied by the hermit. 



One of the most frequently described species is the little 

 Nirotho'e nstaci, Milne-Edwards and Audouin, so commonly 

 found on the gills of the common lobster. This, when 

 magnified, is seen to have the ordinary Cv<7o/i.s-like form, 

 only disguised at first glance by the enormous pair of 

 lateral expansions at the fourth segment of the trunk. Its 

 residence makes it more accessible to an inland observer 

 than most of the marvels in this branch of study. Its size 

 alone should endear it to the possessor of a good microscope. 

 Within a total length of two or three millimetres he will 

 find a series of appendages almost in all respects comparable 

 with those of the large fish-parasites presently to be 

 described. But while all this regular apparatus needs skill 

 and care and a good instrument for making out its details, 

 the most remarkable features of the animal are tolerably 

 plain even to unaided vision. Attached to the front 

 segment of the tail part are two relatively enormous baos 

 of eggs. It is with these that the monstrous lateral ex- 

 pansions of the trunk are deeply and doubly concerned. 

 Not only do they form a protecting arch over the ovisacs, 

 but it is from them that the rosy eggs as well as the bags 

 that contain them are derived. Inside each of the great 



* Lichomolgus agilU T. Scott. 



+ Modiolicola insignis, Auririllius. 



X Lomanoticola imolens, T. and A. Scott 



cylindrical outgrowths can be seen a faintly rose-ooloan 

 structure, which is the ovary, and below this a wbitii 

 gland, the source of the cement which forms the ovisa 

 The great carcinologists, Henri Milne- Edwards. Hem 

 Kroyer, and Heinrich Rathke, have all studied wi. 

 admiring care this minute but remarkable organism. 



Far more diilicult to find and diflicnlt to examine are U 

 Choniostomatidx, which like Xlroilmr are parasitic . 

 Malacostracan crnstacea. Their name signifies that tb' 

 have a funnel-shaped mouth. 

 Eyes they need not. With 

 antennnc they are provided, 

 though the second pair is 

 sometimes missing. They 

 have mandibles, two pairs of / 

 maxilliP, and one of maxilli 

 peds. In the matter of 

 trunk-legs Nature has here 

 been thrifty, giving them ir 

 some instances none at all 

 in others two piiirs witli 

 occasional indication of a 

 third. The body shows no 

 segmentation. Trunk and .Vi™/ 

 tail - part are compounded 

 into a sort of globular 

 mass, from which even the head 

 cisely distinguished. Therr -ro 

 capable of laying as m i ■ 

 and of becoming a thn .a e 



spouses. The female i,.i- .. i> -,.^w.-. ,a m r 



known to be fully a quarter of an incn long. an<I in spe « 

 that are not gigantic, csm dwin<lle to about a twenty-) h 

 part of an inch. \Vhen such creatures have to be loc d 

 for in the branchial cavities of smiiU (umacea, or am g 

 the eggs of Amjihipoda, the patience and discemmei if 

 the naturalist are put to a high tc-^t. and the chief i- 

 couragement to a beginner for tackling the ('ho )- 

 stomatidir lies in the luminous English work on the sul 3t 

 by the Danish writer, H. .h Han«<>n. S->m«> idna of » 

 general form and the compar i ' ' ' ^ i le 



may be gathered from the - .< :h 



they do not pretend to rii.r. : f u 



ori 



•od .\udoiuii. 



aot always very \ i- 

 "T»!e? in thi? fan y 



Sphttronella rUgantula, HMftn. A. Fcin»lo. x 27 ; », Male, -'" 

 c, Another m»lc, x I43. Fn>ni Huuen. 



Lest the reader should feel bis imagination crtmpc by 

 too long dealing with objects inordinately small, he »J 

 now be invited to explore a larger field, and. for lat 

 purpose, to provide himself with a few freshly-ca^l 

 sturgeon, thunnies, sharks, sword-fishes, conger eels, in- 

 fishes, and fishing frogs. Of the eo-called fish-lioethe 



