1889.] 



NATURAL SCIENCES OF PHILADELPHIA. 



11 



idae, I found a number of Gregarines remarkable for 

 the small size of the head and hence the species may- 

 be named Gregarina microcephala. The body is 

 clavate ; the head like a watch crystal with a little 

 ball at the summit. Length 0*35 mm. by 01 wide ; 

 head 0-012 long by 0*04 wide. 



It bears a close resemblance to Echinocephahis his- 

 pidus of Schneider, found in Lithobius forcipatus, but 

 in the one described I at no time found digitiform 

 appendages to the head. 



On Anhydrite. — A remarkable occurrence of A nhy- 

 drite was brought to the attention of the Academy by 

 Prof. George A. Koenig. The specimen was found 

 by Mr. Frank Keeley, among the ballast of the Balti- 

 more and Ohio Railroad track south of the tunnel at 

 cephaia. 125 diam. D arD y j D e l. Co., Pa. Upon a rock of granular 

 structure, which was determined to be Diabase, the anhydrite formed 

 a patch about one inch long, one-half inch wide and one-eighth inch 

 thick. It is of a fine pinkish purple color and pearly lustre. The 

 structure is composite, being an aggregate of prismatic individuals 

 showing an obtuse angle. On closer examination it is found that 

 this angle does not belong to a prism in a crystallographic sense. It 

 is made by two cleavage planes of unequal cleavability, intersecting 



at about 130°. In the adjoining 



( \% 



Fig. 4. 

 Gregarina micro- 



\ 



oP 



oon 00 



>p< 



figure the fragment which was 



measured is projected on the ba- 



50*5' sal plane (oP). The cleavage 



along coPoo is less than along 



coPoo (which reflected a perfect 



image). The cleavage along oP 



is good. The cleavage along 



00P is not mentioned in Dana's 



Handbook. 



Specific gravity = 2-949 (0 ,g 938 substance). B. B. fuses at thin 

 edge to a grayish white enamel, coloring the flame orange. Strong 

 hepar reaction, no color with fluxes. At red heat the color is de- 

 stroyed. No water in the closed tube. Dissolves in strong HCL. 

 Analysis gave : 



Ignition 0-0018 ; BaSo 4 = 0-3355 ; 



A. Substance 0"207 gr. 

 CaO = 0-838. 



B. Substance 0-6463 gr. 

 CaO = = 0-2575. 



Ignition = 

 Insoluble = 



SO 3 = 



0-0025 insoluble ; BaSo 4 =1-0485 ; 

 A B 



0-90 0-90. 



0-40 0-40. 



55-80 55-78. 



CaO 



= 40-49 



39-84. 



97-59 



96-92. 



