34 Messrs. Jones and Kirkby on Carboniferous Entomostraca. 



that figs. 16 and 17 are intended to represent Beyrichia hituher- 

 culata, M'Coy, sp., which is sparingly found in the Calderside 

 shale together with Kirkbya tlrei, Jones, which Ure produces 

 in fig. 21. It is strange that he should have made this mistake, 

 as the two shells are quite distinct to the naked eye under every 

 aspect.^^ 



1834. Hibbert.— In 1834, Dr. Hibbert brought to the notice 

 of the British Association at Edinburgh, and in 1836 he described, 

 in the ' Transactions of the Royal Society of Edinburgh ' (vol. 

 xiii,), some Entomostraca from the Carboniferous strata near 

 Burdiehouse, which are rich in these minute carapaces, mostly, 

 however, belonging to one species*. At page 179 of his memoir 

 he gave small woodcut figures of his Cypris Scotoburdigalemis, 

 and at page 180 others of his Daphnoidia. The latter received 

 the name of " Hibberti " in Morris's ' Catalogue of British Fos- 

 sils,' first edition, 1843. Dr. Hibbert's specimens were again 

 noticed by Mr. L. Horner in the ' Edinburgh New Philosophical 

 Journal' for April 1836, and were regarded as indicating an 

 estuarine (and not a freshwater) origin for the strata containing 

 them. 



Among the many Carboniferous specimens lent to us by our 

 friend Mr. E. W. Binney, F.R.S., are several bearing minute 

 Entomostraca that were in Dr. Hibbert's collection. In these, 

 " Cypris Scotoburdigalensis " is abundant ; but Daphnoidia, un- 

 fortunately, does not appear. Nor can we form a satisfactory 

 conclusion as to the nature of this little fossil from Dr. Hibbert'g 

 woodcuts. The so-called " Cypris" is readily recognized to be 

 a dwarf Leper ditia, with the characteristic muscle- spot, and 

 possessing even the hump on the back of the left valve, so 

 marked a feature in some members of that genus. Excepting 

 in relative size, no distinction can be discerned between Leper- 

 ditia Scotoburdigalensis and L. Okeni; and we find very many 

 gradations in size among these little Leperditia of the Carboni- 

 ferous shales and limestones, including L. Okeni as a large form 

 and L. Scotoburdigalensis as the smallest. Two or more of these 

 varieties are often associated together, sometimes probably as 

 young and old conditions, but often as varieties determined by 

 mode of growth. Some slight difi'erences in the outline of the 

 valves, or in the profile of the carapace, occasionally accompany 

 variation in size ; and, taking these together, we use them as 



* In more than one of the many samples of the Burdiehouse limestone 

 and shale that we have examined, we have noticed what appears to be a 

 more elongate (and Cj/^Jiere-like) form than Leperditia Scotoburdigalensis', 

 but the specimens are so imperfect as not to be determinable. We may 

 say the same in respect to other crushed specimens from this locality, that 

 resemble Beyrichia subarcuata, Jones. 



