July 1, 1898.] 



KNOWLEDGE. 



145 



>r^llHISTRATED MAGAZINE << 



Founded in i88i by RICHARD A. PROCTOR. 



LONDON: JULY 1, 1898. 



CONTENTS. 



The Karkinokosm, on World of Crustacea. — IV. By 

 the Kev. TnoM.\s R. E. Stebbing, M.A., f.b.s , p.r..3. 

 (Illustrated) 



A Classic Legacy ot Agriculture.— II. By John Mills. 

 (Illustraled) 



"The Mimic Fires of Ocean." By G. Clabke XniALL, 



B.SC 



The Petroleum Industry.— II. By Gteoege T. Hollowat, 



ASSOC. K.o.s. (lOND.), F.i.c. (Illustrated) 



On the Eclipse Theory of Variable Stars. By Lieut.- 



Colon>-1 H. K. JiAEKWiCK. F.R.A.s. [Til Ksl rated) 



The Recent Eclipse.— The Lick Photographs of the 



Corona. By E. Walteb llArNDKB, f.e.as. (Plate)... 

 Notices of Books 



Short Notices 



Books Received 



Obituary 



Letters :—W. H. S. MoscK ; J. E. aoBE 



Science Notes. (Illustrated) 



Self-Irrigation in Plants. By tlu> Rev. Alex. S. Wilsox, 



M.A., B.SC. {Illustrated) ... ... ..7 



British Ornithological Notes. Conducted by Habbt F. 



WiTHEEBT, r.Z.S., M.B.O.U 



Botanical Studies.— IV. Mnium. By A. YArGHfN 



Jesnixgs, F.L.S., F.G.s. (Illustrated) 

 Notes on Comets and Meteors. By W. F. DENNnra, 



F.E.A.S 



The Face of the Sky for July. By A. Fowibb, f.b.a.s. ... 

 Chess Column. By C. D. Locook, b.a 



145 



148 



loO 



151 



1.5.3 



135 

 156 

 157 



157 

 158 

 159 

 159 



1150 



HJ2 



163 



166 

 167 

 167 



THE KARKINOKOSM, OR WORLD OF 

 CRUSTACEA.-IV. 



By the Rev. Thomas, R. R. Stebbing, m.a., f.k.s., f.l.s. 



SEEING that the mammalian tail is allowed to con- 

 tract or expand the number of its joints at discre- 

 tion, it looks like a kind of obstinacy in natural 

 arithmetic that has assigned seven vertebrse alike 

 to the neck of the hippopotamus and the neck of 

 the giraii'e. Attention has already been drawn to a similar 

 case of numerical persistence in the Karkinokosm. The 

 whole of the great and diversified sub-class of the Malacos- 

 traca is bound together by the circumstance that the body 

 segments never exceed twenty-one, and only fall short of 

 that number when motives of personal convenience have 

 induced a broad Cancrid, for example, to consolidate, or a 

 threadlike Caprellid to relinquish, some of its somites. 

 But the other great sub-class, the Entomostraca, prefers 

 always to have a number of body segments greater or 

 smaller than twenty-one. Between these two sub-classes 

 some authors give an independent position to the little 

 group of the Nebaliidse. 



Xebaliu hipes has a wide distribution in the northern 

 hemisphere. You may find it at Spitzbergen and in the 



Mediterranean. You may find it also under stones on the 

 south coast of Devon, always exquisitely neat, however 

 untidy the surroundings may be. In this half-inch of 

 animal organism there can be counted twenty pairs of 

 appendages, exactly the full number allotted to the Mala- 

 costraca, and implying a corresponding number of segments ; 

 but at the tail end of this creature there are two extra 

 segments and a pair of caudal branches. Moreover, in 

 Xihalia the eight pairs of limbs which follow the maxilljc 

 are all of a peculiar pattern. The leglike character of the 

 main stem is overshadowed by the great leaflike expan- 

 sion of the subsidiary branches, which have a respiratory 

 function : they act as branchiae or gills. 



Though in Crustacea the gills are commonly enough 

 connected with the feet, yet the order Branchiopoda has a 

 special claim to take its name from this connection, because 

 the branchial character of the feet, instead of being, as 

 elsewhere, subordinate or modestly withdrawn from view, 

 is here monstrously developed and prodigiously obtrusive. 



The order Branchiopoda is so extensive a division of the 

 Entomostraca that it has to be again divided into four sub- 

 orders, with names that may not sound to all ears alluringly 

 mellifluous, but which are moderately handy and in their 

 measure significant. The four names are Phyllocarida, 

 Phyllupoda, Cladiicera, Branchiura. These names, being 

 interpreted, are Leafy Shrimps, Leafy Legs, Branching 

 Antennae, Gill Tails. Unfortunately the interpretation 

 needs an interpreter, just as it is not enough for us to 

 know that Hiawatha is the Teacher, and that his wife's 

 name, Minehaha, means Laughing Water, or that Mudje- 

 keewis is the West Wind, and that the Kingdom of 

 Ponemak is the Land of the Hereafter. The poet needs 

 five or six thousand lines to unfold the story of these 

 names, and to bring the hero to the haven where he 

 would be. 



The Phyllocarida are represented by the border tribe of 

 the Nebaliidffi. Till the voyage of the Cludlemjer that 

 little group contained but one genus. Now it has three, 

 and it is a curious thing that in one of the two new forms 

 the breathing legs are exceedingly long, while in the other 

 they are exceedingly short, the old northern genus standing 

 intermediate between them. 



At no great distance from the Phyllocarida may be set 

 the Phyllopoda, with a name that differs little from theirs 

 either in sound or sense. It refers to the same feature in 

 their construction — the leaflike limbs. The Phyllopods 

 have been dinded into three groups, closely connected, 

 but, in one respect, singularly unlike. One set have a 

 dorsal shield, leaving a long caudal part exposed ; another 

 set are enclosed in a pair of valves in such a way that they 

 might well be mistaken for little molluscs ; whUe the third 

 set are really quite too informal, almost indecorously 

 negligent of the conventionalities observed by the respect- 

 able class of Crustacea. These have no dorsal shield, no 

 ' covering valves, no encrusting carapace ; but each swims 

 about unencumbered, a vagrant " neat and slim, without a 

 rag to cover him." 



Of the last-mentioned group two forms were at one time well 

 known in England, though of late years no one seems able 

 to come across them. One of these, Artemia sa/ina, the brine 

 shrimp, occurred at Lymington, in Hampshire, myriads of 

 these graceful little creatures curvetting and gambolling 

 about in the strong brine of the salterns. They are not 

 marine animals. None of the known Phyllopods exist in 

 the sea. Not too many tears need be shed over our lost 

 Lymington specie^, for it is known to inhabit in countless 

 numbers shallow brackish- water ponds along the shores of 

 Europe, and a very similar form abounds in the Great 

 Salt Lake at Utah, in the United States of America. Our 



