666 



MR. B. N. PEACH ON THE FAUNA OF THE [Nov. 1 894, 



PI. XXXI. figs. 1 and 2 show what appears to be a broader form, 

 but it has been distorted first by having the first two free segments 

 ' telescoped ' into the head-shield, and by having the body folded 

 upon itself at the eighth free segment, the dorsal tubercle of which is 

 well seen against the matrix at the fold. By a fortunate breaking- 

 away of part of the test which adheres to the counterpart, the 

 pleura of the hindermost segments and the greater portion of the 

 telson can be observed at a lower level in the matrix. Since it has 

 been embedded, the specimen has been further broadened and dis- 

 torted by faulting of the matrix. 



Table of Measurements of Olenellus reticulatits. 





M. 4076*. 

 PI. XXX. 



flg.l. 



M. 4104d. 

 PI. XXX. 



fig. 2. 



M. 4161<". 

 PI. XXX. 



fig. 4. 



M. 4142<). 



PI. XXXI. 



figs. 1, 2. 



M. 4078d. 



PL XXXI. 



g.3. 



M. 4093*. 

 PI. XXX. 



fig. 5. 



Full length of parts pre- 



mm. 



29 

 50 



mm. 



33 



46 



mm. 



50 



60 

 40 



40 



22 



mm. 



50 



33 

 36 



20 

 15 



mm. 



27 



24 

 20 



mm. 



27 ' 

 40 



Length of head-shield ... 

 Breadth of do. 



,, eight segments 

 Breadth of third segment 

 Length of spine of do.... 

 Length of telson visible. . . 



Olenellus gigas, sp. nov. (fig. 1, p. 667). 



Fragments of a large species of trilobite with a strong genal spine 

 and reticulated ornament were figured in a former paper (op. jam 

 cit. pi. v. figs. 12, 12 a, 12 6). In the present collection a specimen 

 occurs which gives most of the detail of the dorsal aspect of the 

 head-shield : this is much wider compared with its depth than in 

 O. La/pworthi and 0. reticulatits. It is further distinguished from 

 the latter by its broad margin and strong genal spine. The orna- 

 mentation is readily seen, even with the unaided eye. As stated 

 in the former paper, the pattern of the reticulation is more elongated 

 on the margins and spines than on the general surface, but this 

 applies equally to all the species of Olenellus. 



Portions of cheeks and genal spines of individuals nearly as large 

 as the above, on which the pattern of the ornamentation is much 

 smaller proportionally to their size, occur in the collection. 



Measurements of carapace of Olenellus gigas, M. 1154 d : — 



Length of head-shield 52 mm. 



Breadth of do. 106 mm.: 



:4i inches. 



Olenellus intermedius, sp. nov. (PL XXXII. fig. 7.) 



This species is founded on a single head-shield, preserved in relief 

 in a decomposing ochreous bed, and its counterpart. It is doubtfully 



