244 



KNOWLEDGE 



[November 1, 1898. 



Lomanoiicola insolens. From A. Scott. 



the sphere of its activity is so limited.* Another,! 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 insulens. ] 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.noantennffi 

 or mouth- 

 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 Coprpoda. 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 

 Nicotho'e (istaci, Milne-Edwards and Audouin, so commonly 

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

 magnified, is seen to have the ordinary Ci/< /oyw-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 bags 

 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 agilis T. Scott. 



+ Modiolicola insignis, Aurivillius. 



X Lomanoiicola insolens, T. and A. Scott. 



cylindrical outgrowths can be seen a faintly rose-coloured 

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

 gland, the source of the cement which forms the ovisac. 

 The great carcinologists, Henri Milne-Edwards, Henrik 

 Kripyer, and Heinrich Rathke, have all studied with 

 admiring care this minute but remarkable organism. 



Far more difficult to find and difficult to examine are the 

 Choniostomatidft', which like KicoOidi' are parasitic on 

 Malacostracan Crustacea. Their name signifies that they 

 have a funnel-shaped mouth. 

 Eyes they need not. With 

 antennse they are provided, 

 though the second pair is 

 sometimes missing. They 

 have mandibles, two pairs of 

 maxilliE, and one of maxilli- 

 peds. In the matter of 

 trunk-legs Nature has here 

 been thrifty, giving them in 

 some instances none at all, 

 in others two pairs with 

 occasional indication of a 

 third. The body shows no 

 segmentation. Trunk and yicothoc 

 tail - part are compounded 

 into a sort of globular 



mass, from which even the head is not always very pre- 

 cisely distinguished. There are females in this family 

 capable of laying as many as twenty-eight packets of eggs, 

 and of befoming a thousand times as big as their amiable 

 spouses. The female herself, in giant species, is never 

 known to be fally a quarter of an inch long, and in species 

 that are not gigantic, can dwindle to about a twenty-fifth 

 part of an inch. When such creatures have to be looked 

 for in the branchial cavities of small C'amacea, or among 

 the eggs of Amphipoda, the patience and discernment of 

 the naturalist are put to a high test, and the chief en- 

 couragement to a beginner for tackling the Chonio- 

 stomatida; lies in the luminous English work on the subject 

 by the Danish writer, H. .T. Hansen. Some idea of the 

 general form and the comparative sizes of male and female 

 may be gathered from the subjoined illustrations, though 

 they do not pretend to reproduce the delicate finish of the 

 originals. 



aslaci, Milne-Edwards 

 and Audouin. 



Sphieronclhi eleganiula, Hansen. A. Female, x 27 ; B, Male, x 27 ; 

 c, Another male, x 143. From Hansen. 



Lest the reader should feel his imagination cramped by 

 too long dealing with objects inordinately small, he may 

 now be invited to explore a larger field, and, for that 

 purpose, to provide himself with a few freshly-caught 

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

 fishes, and fishing frogs. Of the so-called fish-lice, the 



