io8 



HARDWICKE'S SCIENCE-GOSSIP. 



are fewer garden flowers which " sport " more freely. 

 That is to say, seeing the genus has run'.to the extreme 

 of floral specialisation, we cannot wonder if we find 

 numerous instances of reversion to some one or 

 another of the stages through which this genus 

 has passed. These may appear as "sports" or 

 " monstrosities." 



The order Scrophulariacese, notwithstanding its 

 exalted floral specialisation, has an exceedingly 

 wide-spread geographical distribution. This means 

 that its members must have been in existence a 

 sufficiently long time, geologically speaking, to allow 

 of their being distributed, through the agency of 

 the numerous geological changes which took place, 

 climatal and physical, during the tertiary epoch. 

 What ups and downs, literally and figuratively, took 

 place over the same terrestrial during the millions of 

 years represented by that period ! We know for a 

 fact that the climate of the tertiary epoch, even in 

 England, began as Tropical, and ended as Arctic. 

 Plants are even more sensitive to temperature than 

 animals. No wonder, therefore, they should respond 

 to these slowly but surely occurring changes by floral 

 and other modifications. All that we know of these 

 are the species of each order left to us. What 

 countless hosts must have gone down in the bitter 

 fight ! All that we know of are the old veterans 

 which have " survived." Perhaps some floral 

 " monstrosities " resurrectionise some of these for- 

 gotten lorms for us — who can tell ? 



J. E. Taylor. 



NOTES ON MARINE MOLLUSCA IN 

 CAPTIVITY. 



By Albert H. Waters, B.A., M.C.S. 



I AM a shell collector myself, so can bear witness 

 to the delights of that pursuit. Nevertheless, 

 I am bound to confess that I find more pleasure, for 

 my part, in investigating the habits of living mollusca 

 than in accumulating specimens of lifeless and shells 

 of defunct and vanished univalves and bivalves. 

 I have long kept living specimens of marine mollusca 

 in my aquaria, and a few notes upon their ways may 

 possibly prove interesting. 



To begin with, the common and well-known edible 

 whelk [Buccinum undatum) is one of the species I 

 have kept in captivity, and I have found that, with 

 care, small specimens will live and thrive for months ; 

 but the dog-whelk {Hima reticulata), so plentiful on 

 our shores, is, as far as my experience goes, hardier 

 than Buccinum undatutn, and lives and flourishes 

 better. Both species like shallow water best, and 

 spend much of their time out of that element, living 

 a sort of amphibious existence, in their fondness for 

 which they resemble the common periwinkle. I 

 feed them generally with scraped meat, and they eat 

 it fairly well ; but their preference is for a piece of 



dead fish or freshly killed mussel. They are noc- 

 turnal in their habits, and I have never observed 

 them feeding in the daytime. By taking a li»ht to 

 the aquarium after dark, they may be observed 

 actively crawling about in the direction of the meat, 

 and their sense of smell is so keen that they soon 

 scent it out ; in the daytime they take no notice of it. 

 Hima incrassata has similar habits, but is perhaps a. 

 trifle less hardy than reticulata. 



Polytropa lapillus I have found requires extreme 

 care in regulating the density of the water, for if 

 it be either allowed to get too salt, or be made over 

 fresh when the loss by evaporation is replaced, the 

 mollusc will die. Its favourite food is a fresh mussel, 

 and it does not take kindly to the scraped meat with 

 which I feed the other carnivorous denizens of my 

 aquaria. 



Periwinkles thrive remarkably well in my vases. 

 I have had the same individuals for ten years, and 

 they breed freely. They must be very long-lived 

 creatures, for they seem to grow very slowly. The 

 young ones are at first quite unlike their parents, 

 and it is quite three years before they begin to 

 assume anything like the familiar form of "a winkle." 

 Their shells are thin, brown, and inclined to a 

 fusiform shape. 



The common periwinkle (Littorina littorea) is the 

 hardiest and most easy to keep, but I have found 

 others of the genus, such as L. rudis, thrive very 

 well and give but little trouble. All the species are 

 very useful ; they are so fond of crawling on the 

 glass of the aquarium that they eat off the minute 

 algae so apt to grow thereon as fast as it appears, and 

 thus help to keep the front of the aquarium clean. 



I cannot now enumerate all the species of mollusca. 

 I have successfully kept. I will merely mention the 

 trochus, the limpet, the chiton, the pholas, and the 

 common mussel. The first-named of these is rather 

 troublesome, the limpet less so. The chiton is very 

 hardy and bears confinement well, and is as useful an 

 inmate of the aquarium as the periwinkle, and for 

 the same reason. I have had under observation in 

 my aquaria Chiton fascicularis, Chiton cinereus f 

 Chiton ruber, and Chiton asellus, but have not 

 noticed much difference in their habits. They are 

 particularly fond of crawling on the glass, and are 

 then very handy for examination with a lens. 



The common mussel is difficult to keep alive for 

 any length of time when introduced in an adult 

 state, but young individuals frequently make their 

 appearance and live a long time. The young mussels 

 are very locomotive, and seldom remain long at one: 

 spot. 



Local Names. — A similar name to that quoted 

 last month for " Water Hemlock," by the Rev. 

 S. A. Brennan, is in use in North Yorkshire. Here 

 all the larger umbellifene are known as " Kelks." — 

 J. A. Wheldon, Leeds. 



