186 



KK OWLEDGE 



[OCTOBEK 2, 1898. 



and coarser than in the latter ; the palate consequently is 

 but little vaulted, and the entire head smaller in proportion 

 to the body. 



The remaining whales of this gi-oup are di\-ided into hump- 

 backs [Mt'i/aptefj) and rorquals or finners {Bnhrnapteru) ; 

 both of which are characterized by the presence of a 

 number of parallel grooAings or flutings in the skin of the 

 throat, by the presence of a back-fin (whence their name 

 of finners or fin-whales), and also by the shortness and 

 coarseness of their whalebone, which is generally of a 

 yellowish colour. Their flukes are, moreover, less expanded 

 than are those of the right whales ; while, as already said, 

 their heads are relatively smaller and lower, with the 

 cavity of the mouth much less vaulted. In their skeletons, 

 the vertebriE of the neck differ from those of the right 

 whales in being longer and completely disconnected from 

 one another ; and in this respect the Pacific grey whale 

 holds a position intermediate between the two groups. 

 Hump-backs, of which there is but a single species, are 

 specially characterized by the shortness and depth of 

 the body, which behind the shoulder rises above the level 

 of the back fin, and by the exceeding elongation and 

 slenderness of the flippers, which are about equal to 

 one-fourth the total length of the animal. The female 

 hump-back, which somewhat exceeds her partner in size, 

 attains a length of from forty-five to fifty feet, or about the 

 same as that of the Greenland whale. An enormous whale, 

 believed to belong to this species, became some years ago 

 entangled in the telegraph cable line off the coast of 

 Baluchistan with three turns of the cable round its body. 

 On the other hand, in the rorquals, the body is long and 

 slender, while the flippers are small and pointed. Of the 

 four well-established species of this genus, the blue or 

 Sibbald's whale (It. silibdldi) — the "sulphur-bottom" of 

 the American whalers — enjoys the proud distinction of 

 being the largest of all known animals, whether living or 

 extinct, attaining the enormous length of from eighty to 

 eighty-five feet ; while the common rorqual (B. iiiusculug) 

 comes in a good second with a length of from sixty-five 

 to seventy feet. Both the others are, however, con- 

 siderably smaller. 



As regards their distribution in time, right whalebone 

 whales have left their remains commonly enough in the 

 pliocene strata of all parts of the world, and they probably 

 also occur in those of the miocene period ; but, although a 

 single vertebra fi-om the eocene beds of Hampshire has 

 been assigned to a member of this group, there is at 

 present no decisive evidence that they had come into 

 existence at such an early date. Since most of the pliocene 

 species are of smaller dimensions than their living repre- 

 sentatives, it appears that these marvellous creatures had 

 only attained their maximum size shortly before the time 

 when their very existence was to be threatened by the 

 relentless hand of man. 



Formerly the only members of this group of whales 

 which were thought worthy of general pursuit were the 

 right whales ; the shortness of their whalebone, coupled 

 with their relatively small yield of oil, and their tre- 

 mendous speed, rendering the rorquals scarcely worth the 

 trouble and risk of hunting. Of the two right whales, the 

 Greenland species, as being the more abundant, received 

 the greatest share of attention ; and so relentless has been 

 its pursuit, that it is now either well-nigh exterminated 

 from many of its ancient haunts, or has retreated still 

 farther north to regions almost impossible of access. As 

 showing how the constant persecution in the Greenland 

 seas has told upon the size of the comparatively few 

 remaining individuals of this species, it may be mentioned 

 that the eleven specimens killed there during the season 



1890-91 yielded an average of less than 8 cwt. of whale- 

 bone, whereas in five taken during the same season in 

 Davis Strait the average yield was more than double this 

 amount. In consequence of this diminution in the number 

 and size of the Greenland whale, the price of whalebone 

 has of late years gone up enormously ; and whereas 

 some time ago whalebone of over six feet in length sold at 

 £1000 per ton, in 1892 it had reached the enormous price 

 of upwards of £2800 per ton. The southern right whale 

 yields a smaller quantity of less valuable whalebone, now 

 selling at ft-om £1000 to £1800 per ton; the quantity 

 obtained from a well-grown example varying from 800 to 

 1200 pounds. The amount of oil produced by a whale of 

 the same species averages from eight to fourteen tons, 

 of which the present market value is about £28 per ton. 

 If the unfortunate animals are not allowed some respite, 

 it is only too probable that the supply will before long 

 cease altogether. 



As another result of this growing scarcity of the Green- 

 land whale, attention has been directed to the previously 

 despised rorquals and hump-backs ; the employment of 

 steam whaling vessels, and the use of explosive harpoons, 

 having enabled the whalers easily to cope with the greater 

 speed of these cetaceans. At Hammerfest, a special 

 " fishery " has, indeed, been established for the capture of 

 rorquals, where the capture of these animals is now large. 

 The products of these whales are, however, nothing like 

 the value of those of the Greenland species ; and if the 

 latter, together with the southern right whale, be so nearly 

 exterminated as to render pursuit no longer profitable, 

 the supply of long whalebone will absolutely come to an 

 end. 



Cannot, we ask, something be done to check this short- 

 sighted greed, before the opportunity is for ever lost ? 



GALLS AND THEIR OCCUPANTS.- 



By E. A. Butler. 



-IV. 



FOR our next illustrations of gall formation we must 

 look to a type of insect very different from those 

 we have already examined. The aphides, or 

 plant-lice, from the very nature of their food, the 

 juices of plants, which they obtain by puncturing 

 the twigs or leaves, necessarily more or less modify plant 

 growth and produce shrivellings and distortions of various 

 kinds. Such a result may be expected to follow the attacks 

 of all species, but some go farther than this and produce 

 actual galls, which externally closely resemble those 

 caused by other kinds of insects. The natural history of 

 this group is so peculiar that it will be necessary to sketch 

 the plan of their development before the connection of the 

 galls with the insects can be properly understood. There 

 are many different kinds of aphides, and everyone is pro- 

 bably familiar with their general appearance. The soft 

 green bodies, commonly called "green fly," which cluster 

 in sticky crowds round the softest and tenderest shoots of 

 rose trees, and the black ones which crowd equally thickly 

 round the tojis of broad-bean plants, are, perhaps, two of 

 the most familiar examples. They form a well-marked 

 division of the order Homoptera, which are distinguished 

 from other insects by having four wings of a more or less 

 similar appearance, and a pointed beak containing four 

 fine piercing needles, and by passing through an incom- 

 plete metamorphosis — that is, never becoming a limbless, 

 resting chrysalis, but having legs and remaining more or 

 less active all through their life. 



Assuming, then, that we know what sort of insects we 

 are speaking about, let us take, to illustrate the group, the 



