December i, 1910] 



NATURE 



133 



uur own; indeed, the fruit crops are identical, whilst 

 .11 our well-known vegetables are included amongst 

 those cultivated in America, but there are some which 

 are not familiar to us, including such as the sweet- 

 potato. Rutabaga (a kind of turnip), watermelon, 

 pepper, and okra. The okra is a plant belonging to 

 the cotton family, and the green pods are used for 

 making the well-known gumbo soup common in the 

 southern States. The pods are also used for stews, 

 and they are preserved by dr}-ing for use in winter. 



The book concludes with a chapter containing cul- 

 tural reminders for every month in the year, both for 

 the northern and southern States, the requirements 

 differing somewhat widely owing to the great differ- 

 ences in the climate. 



The volume is freely illustrated, and it contains 

 twenty-five plates which are reproductions from 

 photographs. Beyond these there are numerous 

 illustrations in the text, most of them from sketches, 

 and, taking them generally, they are very inferior, the 

 figures of apples and other fruits being particularly 

 inadequate and disappointing. 



.4 TREATISE ON BRITISH NUDIBRANCHIATE 

 MOLLUSC A. 



A Monograph of the British Xiidibranchiate Molhisca, 

 with Figures of the Species. Text by Sir Charles 

 Eliot, K.C.M.G. Figures by the late Joshua Alder 

 and the late Albany Hancock and others. Part viii. 

 (Supplementary). Pp. vi+ 197 + 8 plates. (London: 

 The Ray Society and Dulau and Co., 1910.) Price 

 255. net. 



THIS "'supplement " to a work issued half-a-century 

 ago has been admirably conceived and written 

 by the Vice-Chancellor of Sheffield University. Alder 

 and Hancock's classfc monograph is known to every 



narine zoologist, and fifty years of research and 



riticism have found scarcely one weak place or error 

 in that accurate and beautiful treatise. The authors, 

 however, had accumulated certain addenda which they 

 would probably have eventually published in the pre- 

 ;sent form of a supplement. They knew that certain 

 of their descriptions were not sufficientlv full or were 

 not based on a sufficiently large number of specimens 



'^ be final. Moreover, two generations of zoologists 

 could scarcely fail to add new forms to a fauna that 

 was published between 1845 ^nd 1855. or to discover 

 new points in the natural history and anatomy of 

 these attractive moUusca. Hence the need for the 

 present volume, and hence its matter. The illustra- 

 tions are largelv drawn by Alder and Hancock, and 

 have been kept, in the long interval since they were 

 made, in the Hancock Museum at Newcastle-on-Tvne. 

 Sir Charles Eliot has had them reproduced and added 

 to. His long and extensive acquaintance with the 

 subjects and its literature in many lands has qualified 

 him to write a text that shall worthily compare with 

 that of the seven previous parts. The result is one 

 upon which the author and the Ray Societv may be 

 warmly congratulated. 



Few occurrences make such a pleasurable impres- 



ion upon a zoologist as one's first encounter with a 

 member of this group of animals. On turning over 

 NO. 2144, VOL. 85] 



a stone from the heap that lies covered by laminarian 

 fronds, a grey, slimy object disengages itself from 

 the rich animal undergrowth, and on transference to 

 a vessel of water, straightens out its foot, erects its 

 sensitive "feelers," and waves its serried "cerata." 

 The slimy blob has become a superbly coloured 

 eolis, or an Aegirus punctilucens , with coloured light 

 emanating from the sparkles on its mantle. Such a 

 transformation is not readily forgotten, and when 

 the attraction of nudibranchs has once been felt, it is 

 not easy to resist the temptation to investigate so 

 many of these creatures as can be examined in a 

 state of nature. The search for them takes one into 

 the rich pastures of the sea, and here they must be 

 found only by acquaintance with the special haunts 

 of each several kind. The sea, like the land, has its 

 seasons of plenty and of poverty. In winter and 

 early spring few nudibranchs are to be found in the 

 laminarian beds, where later they will abound. A 

 few Doris, perhaps, no two alike in colouring, and 

 an Eolidia papulosa, may be found gnawing the base 

 of a sea-anemone or winding that pink gelatinous 

 band of eggs which is to people the water with quaint 

 free-swimming larvae. But as spring comes, the 

 nudibranchs increase in number, and proceed at once 

 with the great business of procreation. The hydroids, 

 sponges, or alcyonium are the special resorts of Doto, 

 Doris, and Tritonia. Others affect sea-weeds, and 

 are scarcely to be detected in the axils of their food- 

 plant. One kind, a glutton, is found only on the 

 eggs of certain fish. Another eats out the soft parts 

 of a sea-squirt, and then lies buried in the eviscerated 

 tunic. Altogether in the British area there are more 

 than a hundred species, a synopsis of which forms the 

 last portion of this work. 



The mode of treatment may be shortly summarised. 

 First comes a chapter on variation and distribution. 

 In colour particularly nudibranchs offer a consider- 

 able range of variation, in part due to food, in larger 

 part to light-factors that have as yet not been 

 examined. Age differences between individuals of 

 the same species introduce another source of diversity', 

 and the phenomena of autotomy among Eolids is a 

 further cause of discrepancy. With regard to distri- 

 bution. Sir Charles Eliot summarises a great mass of 

 evidence in a few pages. The most salient facts are 

 the similarity of the nudibranch faunas in the northern 

 and southern parts of the Atlantic, the similarity of 

 the nudibranchs in the .North Atlantic and North 

 Pacific Oceans, and the distinctness of a tropical 

 fauna in the intennediate zone. 



" It is interesting to see that the waters of the 

 South Atlantic bevond the tropics contain forms very 

 similar to those found in the north, if not identical 

 with them " (p. 1 1). 



Eolids appear to be preponderant in Arctic and 

 Antarctic waters, Doris in tropical waters. With 

 regard to the vexed question of nomenclature, Sir 

 Charles takes up a position intermediate between the 

 " lumpers," such as Alder and Hancock, and the 

 " splitters," such as Bergh, and he has many valuable 

 remarks on the synonymy of the more difficult species. 

 Two interesting chapters follow on the bionomics and 



