Vol. 56.] SPECIES OF OLENTTS. 619 



Olenus Mitcrinsoni, sp. nov. (PI. XXXV, figs. 5 & 6.) 



The specimen under description is about \ inch long; the head- 

 shield and probably part of the thorax are missing. 



The thorax is made up of a number of segments probably 

 greater than ten. Its chief feature is, .that from the centre of the 

 axial part of each segment proceeds a spine of considerable 

 dimensions. Those spines nearer the pygidium are in no respect a 

 less prominent feature than those near the head-shield. The pleurae 

 are grooved, and are sharply bent near their extremities to form 

 posteriorly-projecting spines. 



The pygidium is entire, without a well-marked border, and 

 consists of few segments (four to five). 



Owing to the absence of the head-shield, and the doubt as to the 

 exact number of segments in the thorax, it is perhaps best to refrain 

 from assigning this form to any one of the subgenera of Olenus. 

 I hope before long, however, to be able to describe the head-shield 

 of this interesting species. 



This specimen was presented to the Oxford University Museum 

 by the Eight Rev. Bishop Mitchinson, Master of Pembroke College, 

 and was found by him in the Shineton Shales of Shineton (Shrop- 

 shire). 



EXPLANATION OF PLATES XXXIV & XXXV. 

 Plate XXXIV. 



Fig. 1. Inner cast of Dalmania nob His. Nat. size. 



2. Outer cast of the same. Nat. size. 



3. Dalmania nobilis. Restored. 



Plate XXXV. 



Fig. 1. Head-shield of Dalmania coronata. xO. 



2. A single thoracic segment of D. coronata. x6\ 



3. A complete specimen of D. coronata. x6. 



4. Outline drawing of D. coronata. Restored. 



5. Olenus Mitchinsoni: specimen laterally compressed. X about 4. 



6. Part of a single thoracic segment of the same. X about, 6. 



Discussion. 



The Rev. J". F. Blake and Mr. Lydekker spoke, and Prof. Sollas 

 replied on behalf of the Author. 



