104 



KNOWLEDGE 



[June 1, 1892. 



Such is the wide interpretation given to the doctrine of 

 the permanence of continents and ocean basins. 



The stud_v of the European Chalk, besides the two great 

 lessons to which we have especially directed attention, has, 

 therefore, proved to us the former existence of two great 

 seas, in which the cretaceous rocks were deposited — the 

 northern one being a metre chiusum, cut off from the 

 Atlantic, in which was deposited the white Chalk ; while 

 the southern one, in which the hard, massive limestones of 

 southern Europe were laid down, formed the connectmg link 

 between the Atlantic and the Indian Ocean, to which we 

 have already alluded. We might pursue our subject 

 further, and discuss the origin and nature of the flint and 

 pyrites which are of such common occurrence in the Chalk, 

 or we might direct attention to the more valuable and much 

 rarer phosphates which are sometimes contained in it. 

 We might, again, discuss the peculiar characters of the 

 cretaceous fauna, and show how that of the closed northern 

 sea differed from that of the open southern ocean. We 

 might do all this, and more ; but what has been written is 

 sufficient to show the amount of interest and the many- 

 weighty problems connected even with a " Lump of Chalk." 



ANTS' COMPANIONS.-II. 



By E. A. Butler. 



UNQUESTIONABLY the most curious of aU the 

 beetles that associate with Ants is the little 

 Cliniiifrf(ireol((tiis (Fig. 2), which lives specially, 

 though not exclusively, in the nests of the 

 Yellow Ants (Lasiux r^tinis). It is a shining, 

 hard-bodied, reddish yeUow insect, no more than one- 

 twelfth of an inch long, with a broad abdomen which 

 carries a deep pit in its centre, but a small, narrow, and 

 almost rectangular head. Though 

 belonging to a different family, it in 

 some respects resembles the Brach- 

 elytra, of which we spoke last month, 

 inasmuch as it has, like them, 

 short elytra covering only the base 

 of the abdomen ; but there are no 

 wmgs underneath these, the insect 

 being apterous and unable to fly. It 

 is also mutilated in other respects ; 

 for mstead of the pair of elavs with 

 which each foot of an insect usually 

 terminates, only a single one is 

 present on each. The small size of 

 the head, again, is partly due to the 

 absence of eyes, for the beetle is quite 

 bhnd ; but, apparently to compensate 

 for the loss of this one function, the 

 other organs of sense, the antenn;e, 

 are exceptionally large, thick and club-shaped, suggestive 

 of a high development of whatever sense, whether of smell, 

 touch, or any other, resides in them. Further, the beetle 

 seems to have lost the power of feeding itself, for its 

 guardians feed it in the same way as their own young, 

 and its mouth organs are quite rudimentary. Here then 

 we have an insect which has lost the powers of flight and 

 sight and of helping itself to food, and which woukf plainly 

 be doomed to speedy extinction but for the fosterincr care 

 of the Ants. We have spoken of its havmg lost the above 

 powers, advisedly ; for though there is of course no direct 

 evidence on the subject, yet when we compare the insect 

 point by point with other members of the same family 

 which do not make it the rule of their life to practise 

 parasitic habits, and are in full possession of all their 



Fig. 2. — Clavigei- 

 foveolatus, a blind 

 beetle found in Ants' 

 nests; magnified fonr- 

 teen diameters. 



Tnp --■ 



-??ip 



Fie. 3. — Head of Psdaphus HeUii for 

 comparison with Claviger. a antennfe, 

 »)p maxillarv palpi, e eyes. 



powers except that of flight, and when we see how 

 exceptionally well developed their eyes and feeding 

 apparatus are, it seems impossible to resist the conclusion 

 that in Claviiier, which, while unlike them in these 

 respects, closely resembles them in others, we have an 

 instance of the suppression of parts through disuse. The 

 family in question is called Psehtphidir, and is represented 

 by a large number of small species in different parts of 

 the globe ; in this country we have a little more than 

 thirty kinds, all minute insects, Claniier being one of the 

 largest. Many of them are common, and they may be 

 found in moss, under stones, amongst dead and decaying 

 leaves, in refuse heaps, &c. They have strong, sharply- 

 notched jaws, and are carnivorous in habits, being supposed 

 to feed chiefly on mites. Fig. 3 shows the head of one of 

 the commonest of 



the Fseliijiliiild-. ^-(^-^^ 



In it we may 

 specially note the 

 extremely promi- 

 nent, mulberry- 

 like eyes, and the 

 very long maxil- 

 lary palpi, which 

 look like a second 

 pair of antennse, 

 in extraordinary 

 contrast to the 

 mutilated condi- 

 tion of the head 

 of Claviiier. This 

 is the condition 

 of most of the Pselajiliiiln , and it shows what might have 

 been expected in Chirujer, but for its parasitic habits. It 

 will be observed that, though Clarujer has very stout 

 antenniP, the number of joints is much less than in the 

 rest of the family. 



This remarkable little beetle carries at the outer corner 

 of its elytra certain tufts of yellow hairs, which the Ants 

 have been observed to take in their mouths and lick, 

 sometimes continuing the operation for eight or ten 

 minutes at a stretch. The hairs apparently yield some 

 kind of secretion which is agreeable to the Ants' sense of 

 taste, and thus one can easily understand that "cupboard 

 love " will operate strongly in the direction of inducing the 

 Ants to take the greatest care of their interesting charges. 

 The extreme importance of these tufts of hairs and their 

 secretion to the little beetle is evident ; its life, as a 

 species, literally hangs on these threads, and this very 

 fact tends in the direction of improving the organs, and 

 thus securing to the species a more certain tenure of life. 

 The beetles are found in those nests of the Yellow Ant 

 which are constructed under stones, especially in the 

 chalky districts of the South of England, but apparently 

 not in those that are under turf. The beetles are attended 

 by the Ants, and carried about from place to place as 

 occasion requires, though of course they can walk them- 

 selves if they choose ; their pace, however, is but sluggish. 



We have already pointed out that Clarir/er is not to be 

 found in all the nests of the Yellow Ant ; the same remark 

 holds good of the other species of Ants with which it may 

 be associated. Lespes has made the observation that 

 specimens of the beetle which had been removed from a 

 nest of the common Garden Ant {L. niijer], on being trans- 

 ferred to another nest belonging to Ants of the same kind, 

 but in which no such pets were kept, were destroyed and 

 eaten, instead of being cherished. He concluded that this 

 was an indication of their failure to comprehend the use 

 of the beetles, and that therefore different communities 



