142 ON PEEMIAN ENTOMOSTRACA FROM 



determinations, I must acknowledge the kind assistance of Mr. 

 Jones. 



Though the surface of this species is described as being 

 smooth, Mr. Jones informs me that he has seen traces of pittings 

 on some specimens from Kamsdorf, Germany; he has also ob- 

 served similar traces on examples of B. ampla, from Hampole, 

 Yorkshire. 



When Mr. T. R. Jones described the first-discovered speci- 

 mens of this species, he referred them to the B. curta of M'Coy — 

 a species found in the lower carboniferous rocks of Ireland. 

 Subsequently Dr. Reuss met with more typical specimens in 

 Germany, which he described, and named Bairdia |9Ze5e?a. In 

 the " Annals Nat. Hist." of last year, I identified a group of 

 closely related varieties with Dr. Reuss's species, to which I at 

 the same time referred the specimens described by Mr. Jones. 

 However, on afterwards corresponding with the latter gentle- 

 man on the subject, I found that he was still inclined to refer 

 all these specimens to B. curta. After some explanation on his 

 part, and further examination on my own, I was disposed to 

 come to the same conclusion. In arriving at this opinion, both 

 Mr. Jones and myself relied upon the accuracy of Professor 

 M' Coy's figures of B. curta, for up to this time we had not been 

 able to examine specimens of that species from carboniferous 

 strata. P'ortunately, however, before the publication of these 

 remarks, Mr. Jones received the type-specimen of M'Coy, which, 

 when he had carefully extracted it from its matrix, so as to show 

 its true form, proved to be a species distinct from the Permian 

 examples. The figure given by M'Coy (" Syn. Char. Carb. 

 Foss.," Ireland, pi. 23, fig. 6) does not represent the exact out- 

 line of the specimen, but as it appeared when partly imbedded 

 in matrix. 



In B. curta, the anterior extremity is acute, and differs little 

 from the posterior extremity, except in being less produced. In 

 B. pleheia, the same feature is always comj^aratively broad, 

 and more or less blunt; or, to speak more precisely, the gradual 

 antero-dorsal slope, and the quick upturn of the angle, conjoin 

 in giving this extremity what Mr. Jones graphically terms a 



