Buckman — Method of Removing Tests from Fossils. 163 



Art. XVII. — A Method of Removing Tests from Fossils ; by 



S. S. Buckman. 



The following remarks apply especially to brachiopods ; but 

 tliere is reason to believe that the method may be extended 

 with advantage to other classes of fossils. Among brachiopods 

 natural casts are not frequently met with, except in a few 

 favored localities; and the natural casts are often unsatisfac- 

 tory. Therefore a method of making artificial casts by removal 

 of the test becomes of value when it is desired to study internal 

 characters. The following is the method : 



Choose specimens which are not crystalline, and preferably 

 those which are likely to have a coarse-grained, hard internal 

 core. Heat them to redness and then drop into water. 

 Much of the test will then fall off ; what remains can some- 

 times be wholly removed by brushing. If not, the delicate use 

 of a sharp penknife will separate the rest. Care must be 

 employed in using the penknife to prevent scratching of details 

 of muscle marks, ovarian area, or vascular markings. 



Heating may be done in an ordinary fire, but it is not alto- 

 gether satisfactory; the specimens may be burnt too much. 

 Heating by means of a bunsen flame, or a spirit lamp, or for 

 larger specimens a gas or spirit blow-lamp, is more satisfac- 

 tory. As the test is most adherent over the muscle areas, they 

 should be heated most ; that is, the specimens should be held 

 beak downwards 1 in the flame in the case of brachiopods. 



Experiments so far have been chiefly with Mesozoic brachio- 

 pods, and of these the Rhynchonellids come out most satisfac- 

 torily, presumably on account of their fibrous test ; some of 

 them make very beautiful casts, showing all details excellently, 

 but, of course, much depends on the state of fossilization. The 

 Dallininse have also yielded satisfactory results, but for some 

 reason the Terebratulids do not come out so well, and the pro- 

 portion of spoilt specimens is considerable. 



In the case of rare specimens the method should only be 

 employed after careful consideration ; there is, of course, a risk 

 of destroying the specimen altogether, and in any case details 

 of test, of beak, deltidial plates, etc., will be lost. 



The method was suggested by receiving, for description, 

 from the Geological Survey of India a series of brachiopods 

 from Burma, which had been burnt by Mr. T. D. La Touche 

 for the purpose of extracting them from a rather intractable 

 matrix. Many showed as a consequence good internal details, 

 and that fact suggested burning other species to compare with 

 them. 



Thame, Oxon, England. 



