160 MATTHEW ON CAMBEIAN 



near the anterior end. Marginal furrow rather broad, strongest near the anterior end, 

 fading out towards the posterior, where the edge of the shell is bent oirtward. Dorsal 

 valve less ventricose, showing an eye-spot faintly elevated on the upper anterior part. 



Sculpture. — Closely set, strongly marked pits, which are most distinct on the ventricose 

 part of the shell. The pits along the margins, and around the eye spots are smaller than 

 elsewhere. 



She. — Length, 11 mm. ; height, 8 mm. ; depth, 4 mm. 



Horizon and Locality. — In the dark grey sandstones of Div. 1 a' at Hanford Brook, St. 

 Martins. 



Leperditia Ste.\di, n. sp. (Plate VII, figs. 13 a-c.) 



Oval, lenticular, rather flat, hinge line more than two-thirds of the length. 

 Marginal furrow sharp and the rim well marked at the anterior end, where it is 

 crossed diagonally by a branch of the marginal furrow. 

 Sculpture. — As in the preceding species. 



Size. — Length, 9 mm. ; width, about *7 mm. ; depth, \\ mm. 

 Horizon and Locality. — As the preceding species. 

 Found by Mr. G-eofFrey Stead. 



Note. — Since writing the above article, I liave learned that a suggestion made by me, in reference to Olcndhis 

 Kjerulfi, has met with acceptance from a number of naturalists. Some time since in speaking of the work done by 

 Dr. Gerhard Holm, in developing the remarkable characters of this species, I suggested that his name should bo 

 commemorated in connection with it. 



I am satisfied that, when other species now ranged under Olenellus and Olenoides are treated as Dr. Holm 

 has treated 0. Kjerulfi, a rearrangement of these forms will be found necessary. One may see for instance 

 the mixture of characters by comparing the lately discovered Russian species Olenellus Mickwilzi, Schmidt, with 

 Olenoides typiculis and Mesonacis Vermontia.na. Olenoides, originally based by Mr. i\Ieek on a part of a thorax 

 (and pygidium ?)— 0. Ncvadensis, — assumes an entirely new aspect when referred to O. U/picali.', Walcott, and the 

 original Olenoides may be quite a dillerent trilobite from the latter. While I appreciate î\Ir. Walcott's loyalty 

 to the originator of the name, it .seems to me that he might with advantage, have left this name in abeyance, 

 based as it is on such a defective example. 



The four-spined hypostome of 0. Kjerulfi is different from any known hypostorae of an Olenellus or a 

 Paradoxides. The four points are perhaps the analogues of the four spines at the back of the head-shield in this 

 species. Such a hypostome and the absence of an enlarged third segment of the thorax, separates this species 

 from all the American Olenelli. Mcsonacis differs from it in several important respects, e.g., the enlarged third 

 segment and the great spine on one of the posterior segments. I propose therefore to use hereafter for 0. Kjerulfi, 

 the generic name Holmia. 



