384 



importance is the occurrence of traces of three pairs of very- 

 minute, ill-defined, and perhaps continuous glabella furrows. 

 In the latter characters the replica of "Dolichometopus tatei" 

 and the three examples of "Olenellvs pritchardi" are in- 

 decisive; the neck ring of the most perfect of the M. sub- 

 sagittatus specimens displays a well-marked central tubercle. 



For some time I regarded these three — "Dolichome'topus 

 tatei," "Olenellus pritchardi," and "Microdiscus subsagit- 

 tatus" — as one and the same, and I am not even now sure 

 that I have done right in separating the last named from the 

 other two; however, this course will probably please those 

 who deal in microscopic specific differences. 



Of Tate's illustrations that of "0. pritchardi''' is sub- 

 stantially correct, but that of "M. subsagittatus" is 

 imaginary. 



Loc. and Hot. — Similar to last. 



There is evidence of yet another Trilobite in these Yorke 

 Peninsula Cambrian beds, as previously stated. Some years 

 ago Mr. H. Y. L. Brown, late Government Geologist, pre- 

 sented to the Australian Museum examples of a whitish-grey 

 limestone from Clinton, near the north-west corner of Gulf 

 St. Vincent. Scattered throughout these hand specimens are 

 portions of cephalons, thoracic segments, etc., but all frag- 

 mentary. 



The glabella was of the same elongately-oblong type, 

 slightly narrowing forwards as in the two last described forms. 

 Ther are three pairs of furrows, the basal pair circumscribed, 

 the two anterior pairs short, deep, and apparently not com- 

 plete. The anterior area was very wide, concave, and with 

 upturned limb, and, so far as I can see, an absence of the 

 bridge uniting the anterior end of the glabella with the limb. 

 The fixed cheeks are deltoid more or less ; neck-ring wide with 

 a central backwardly directed spine ; the whole surface is 

 minutely granular. 



I do not think this can possibly be identical with any 

 of the previously described cephalons, allowing for our limited 

 knowledge of their complete structure, unless it be with P. 

 subsagittatus. The very wide and concave area anterior to the 

 glabella and upturned anterior limb seems to point to this. 



Ptychoparia( ?) australis, H. Woodward. 

 PI. xxxix., fig. 6. 

 Conocephalites australis, H. Woodward: Geol. Mag., i. (3), 

 1884, p. 344, pi. xi., fig. 2a, b. 



Sp. Chars. — Glabella oblong, almost parallel-sided pos- 

 teriorly, the lateral margins barely tapering until near the 



