nm 



Retrospective CriticisTii, 



I think it demonstrable that the pearl is not the product of disease; an 

 animal excretion, but moulded from the pearly matter of the shell; the cavities 

 in the interior of the shell, and where the pearls are found to lodge, seem 

 to go far to prove this. The vast size and great variety of form and colour 

 occasionally presented concur in the conjectural probability. They are 

 formed by the animal as plugs to stop up the enemies' mine, — the circular, 

 -&c., perforations of theVenmlithophagus, ilfytiluslithophagus, Pholas dac- 

 tylus, and Mixrex BranddriSy &c. — J. Murray, Carmarthen /April 2. 1830. 

 Leather Coat Jack (Vol. III. p. 80). — Sir, The following extract from 

 Kirby and Spence's Entomology, vol. iv. p. 189., will throw some light upon 

 the history of this wonder-working individual, who appears to have been, 

 by a feat almost as extraordinary, transformed by Mr. Rhind into an insecti 

 " But the grub of Elophilus tenax (a drone-looking fly) affords a more sui'- 

 prising instance of this power of counteraction : — an inhabitant of muddy 

 pools, it has occasionally been taken up with the water used in paper- 

 making, and, strange to say, according to Linne, has resisted without injui*y' 

 the immense pressure given to.the surrounding pulp (jFw. &uec. 1799); likfe 

 Leather Coat Jack, mentioned by Mr. Bell QAnatomy of Expression in 

 Painting, 170.), who, from a similar force of muscle, could suffer carriages 

 to drive gycp tttH without receiving any injury." The circumstance maii 

 tioned by Linnaeus is however more wonderful than the exploits of the abo^d 

 individual; and the authority of the learned Swede is of so high a nature, 

 that but :,littlei /doubt can arise upon the narrative. — J, O. Westwood, 



IchnewmmMcB, — l^^-^B: k)a3C»lfibBl)arffei source of regret to the real lover 

 of nature, that the m6re-irfaiute^«a5Jfeotfeaf)the creation are gener^ly looked 

 upon by the^ professed general natraiiliHfeTiwithS apathy, even if they are not 

 entirely disregarded, as though they were unworthy of attention and in- 

 vestigation. Forgetful that the Icjwest ' infeect or polype, even the meanest 

 atom that lives, the Monas itself, derives importance from occupying a 

 link in the great and complicated chain of the creation, such persons are 

 contented to observe and study objects only whicli attract their attention 

 by thi^ir- splendour or size, or by the benefits or injuries which they discover 

 them to be capable of bestowing or inflicting. It is not however to be 

 denied that many, najr, the majority, of the more minute creatures exhibit 

 " the work, of an almighty hand" in a far more wonderful and interesting 

 manner than their larger brethren, whether we regard the brilliancy of their 

 colouring, the peculiarity of their characters, or the exceeding singularity 

 of their economy. Hence, from such inattention must obviously arise great 

 confusion in the nomenclature of the objects ; and it has hence repeatedly 

 occurred, that the most interesting observations have become lost to the 

 student, from the circumstance of the object being either unnamed or mis- 

 named. Of this confusion existing in the greatest degree, the minute 

 families of hymenopterous insects have perhaps afforded the most preva- 

 lent examples. And I cannot but regret that the communication of your 

 correspondent T. H. (p. 31.) has exhibited an additional proof of this 

 confusion in his nomenclature of the object of his paper, namely, a very 

 small species of ichneumon fly (/chneumon ovulorum of Linnaeus, Platygaster 

 ovulorum of the fam. Proctotrupidae of Latreille. In the first place, it is 

 to be observed, that the name of the insect adopted by your correspondent, 

 /. ovulorum, is sufficient of itself, from its reference to the economy of 

 the species, to prove that it could not be applicable to the insect in ques- 

 tion ; the true /. ovulorum of Linnasus inhabiting, as the name implies, 

 the eggs of lepidopterous insects. Your correspondent's insect is in fact 

 the /chneumon glomeratus of Linnaeus, and its history has been investi- 

 gated by Reaumur, De Geer, Rdsel, &c. &c. In the second place, supposing 

 that your correspondent's insect were the true /chneumon ovulomm, or 

 that he were correct in referring the egg-feeding ichneumon to the genus 



