GRIFFITHIDES. 31 



in front, considerably elevated above the cheeks, narrowed behind to about one 

 half its breadth in front, the tubercles, or projecting portions which connect the 

 eyes with the glabella, forming the remainder of the breadth, divided from the 

 cheeks by well-marked furrows ; it is marked by three nearly obsolete cephalo- 

 thoracic furrows on either side. These are scarcely seen when perfect, but are 

 obvious in the cast ; cast minutely punctured or granulated. Cheeks spherico- 

 triangular, convex, so thickened on the outer edge as to form a distinct border or 

 rim, elevated above the cheeks and rounded, which is prolonged backwards into 

 short pointed spines (they are broken off in fig. 1). This rim or border (' wings ') 

 is marked with sharply raised longitudinal lines, the number varying in different 

 specimens and in different parts of the rim, as they do not extend the whole 

 length (our figures are deficient in showing this). These raised lines are wanting 

 in the cast which is smooth. The raised rim is continued across the cephalo- 

 thorax where it joins the thorax, and is here of the same form and structure as 

 the first transversal segment of the thorax, from which it is sometimes not easily 

 distinguished. In front of the glabella the rim is much smaller than aloug the 

 margin of the wings, and is turned under the margin, forming a flat expansion. 

 Eyes small, suboval, very prominent; when perfect covered with a smooth, 

 corneous, transparent membrane ; but under this very finelj^ and beautifully 

 reticulated, not oblique (the apparent obliquity of the eye being caused by the 

 position of the tubercle or projection which unites it with the glabella), covered 

 above with a distinctly granulated 'velum palpebrale,' the outline of which 

 corresponds to the facial suture. Neck-tubercle frequently seen. 



*' In the furrows which separate the cheeks and glabella, about half way between 

 the front of the eye and the anterior margin, I have observed in all the tolerably 

 preserved specimens which I have seen, a small hole or indentation. These are 

 constant and therefore obviously connected with the structure of the creature, 

 although I cannot offer an explanation of their use. They are similar to those 

 noticed by Portlock in his Ampyx Sarsii} 



" Thorax-joints nine in number; when perfectly preserved the joints of the 

 medial segment or axis appear simple, but are marked internally with a transverse 

 furrow, the joints of the lateral segments (' pleuripedes,' Portlock) are compound, 

 being marked along their centre by a furrow which follows the outline of their 

 form but does not reach the outer margin, and so formed by flattening on the 

 edge as to admit of their folding freely over one another, when the animal was 

 contracted; the axal and lateral lobes are nearly equal in breadth, but differ 

 much in sectional form. 



" Pygidium, a little more than semicircular, middle lobe consisting of eleven 

 costge, divided by well-marked furrows and simple (De Koninck says fourteen, our 

 1 I refer to this structure in my Appendix to Part II. 



5 



