116 Proceedings of the Royal Physical Society. 



about three-fourths of its length from the anterior margin. 

 It is highly vaulted, and is divided by a deep sinuous trans- 

 verse groove into two areas. The smaller of these, lying 

 behind the groove, is rounded and vaulted in both directions, 

 and bears a striking resemblance to the front part of a 

 human skull, while the larger area in front, which bears the 

 eyes and the sockets for the antennse, reminds one of the 

 face. The eye-spots are aggregated on two small, almost 

 circular eminences, which rise up out of hollows situated 

 just in front of the groove above mentioned, and about 4 mm. 

 apart. Owing to imperfect fossilization, and to the difficulty 

 in clearing off the matrix, the number of eye-spots upon each 

 eminence cannot be made out. 



The sockets into which the antennae are articulated are 

 placed in front of the eyes, but somewhat closer together, 

 and are surrounded by raised margins. The space between 

 the sockets and the rounded lip in front are pitted with 

 small circular holes, from which, doubtless, sensory hairs 

 grew during life, but which had been removed prior to 

 fossilization. The antennae are short, and similar to those 

 of the recent lulus. In the present case, only that of the 

 right side is preserved, and that is disjointed and out of place. 

 The three proximal joints, still attached to each other, lie 

 bent round the lip, just within the anterior margin ; while 

 the three distal joints, also attached to one another, lie 

 imbedded in the matrix, a little outside and beyond the 

 right eye. The aggregate length of the six joints is 5 mm. 

 Each segment is almost circular in cross section, and 

 narrowest at its proximal extremity. That nearest the 

 head is the largest, and thence they decrease in size till the 

 fifth is reached. The terminal joint is somewhat elongated 

 compared with the fifth, and ends in a rounded and blunt 

 tip, which is well pitted with circular hollows, as if it had 

 been plentifully supplied with tactile hairs (Fig. 1^). The 

 mouth organs have not been observed. If they still exist, 

 they are deeply embedded in the matrix, which, at that 

 point, is of the nature of a clay ironstone. 



Body. — As already stated, only the dorsal portions of the 

 body-rings are visible. Counting backwards from the head. 



