398 A. JR. Honcood — Archnrenicola Rhcetica. 



Burrows. The shales in which this fossil (specimen A) occurs are 

 commoTily traversed by burrows which may, and in fact almost 

 certainly must, have been the burrows of this Annelid. They are 

 small in comparison, but have doubtless shrunk and become compressed 

 since they were made. Most are horizontal, and if belonging to a 

 worm of the Arenicola type, they belong to the horizontal part of the 

 U-shaped burrow such as it makes in marine sands at the present day. 

 They are irregular and not of great length, though the fragmentary 

 material found can hardly be said to give an adequate idea of their 

 length or true nature. AVhether they were U-shaped or not is not clear. 



Resemblance to a Myriapod, and dijference. There is a superficial 

 homoeomorphy between this fossil and some fossil Myriapods. But 

 there is no telson, no spiracles, no spines, the appendages are different 

 (as are the annulation and segmentation). There are no ocelli, and 

 the walking-feet of such fossils as Acantherpestes and Eupholeria are 

 quite different. Archarenicola bears, indeed, on the whole a distinct 

 Annelid character, whilst the fossils called Myriapods are quite 

 distinct.' 



The only resemblance lies in the fact that there is an outline which 

 is regarded as due to the extrusion of the viscera, comparable with 

 the brown zone that we suggest is due to staining by juices exuded 

 by the Arenicola type of Polychsete. 



Affinities. Having regard to the character of the head portion of 

 specimen A and the paraporlia, there can be no hesitation in placing 

 this fossil in the group Plianerocephala, in which the prostomium is 

 distinct, and the segmentation is of the same type. 



As regards the sub-order to which it may be referred, there is 

 no doubt that the absence of tentacles, palps, and peristomial cirri, 

 and the simple nature of the parapodia which project, place it in the 

 Scoleciformia, amongst which we find the family Arenicolidse. The 

 capillary setae, absence of tentacles, palps, etc., place it in this last 

 family. Whether it should belong to the caudate or ecaudate section 

 is not demonstrable from the material so far to hand, but I should 

 expect from its general characters in other respects that it belongs to 

 the second. 



Specimen B. (PI. XXI, Fig. 1.) 



Size. Extreme length, 8'25cm. ; greatest width, 1cm. 



Measurements hetween anniili. The distance between the annuU is 2 mm. 

 The annuh themselves measure as much, and the furrows between are deeply 

 marked. This specimen is preserved in an indurated sandstone, and the 

 impression is better marked anteriorly as regards annulation, having a less 

 flattened appearance. At the posterior end the annuli are not so far apart. 

 Anteriorly there are five to a centimetre, and each annulus is equidistant, 

 except in one case, where it is 3 mm. distant from the next. For a great part 

 the impression is covered by the matrix, which it is difficult to remove with 

 advantage. Where it is uncovered elsewhere a black slickenside-like covering 

 obscures the seginentation. 



Surface. The anterior portion is an inside cast of the surface, except along 

 the margin, and bears no papillae. The posterior portion is covered by a black 

 slimy covering, which may originally have been slimy bitumen, containing 



' "Fossil Myriopods from the Middle Coal-measures of Sparth Bottoms, 

 Rochdale, Lancashire" : Geol. Mag., 1912, p. 74. 



