EXPLANATION OF PLATE 3. D. 



I CUPRESSOCRINUS * CALYX (M"=Coy). Basal view of specimen, natural size, from the limestone of Der- 

 byshire. 



1 a Profile of ditto. 



2 CUPEESSOCRINUS * IMPRESSUS (M°Coy). End view of specimen, natural size, from the carboniferous 



limestone of Derbyshire. 



2 a Profile of ditto. 



3 PLATYCRINUS VESICULOSUS (M-'Coy). Profile of specimen, natural size, from the carboniferous lime- 



stone of BakeweU, Derbyshire. 



4 POTERIOCRINUS NUCIFORMIS (M'^Coy). Profile, natural size, from the carboniferous limestone of Der- 



byshire. 

 4a Same specimen, seen from the other side. 



5 ACTINOCRINUS {Amphoracrinus) ATLAS (M°Coy). Profile of specimen, natiual size, from the carboniferous 



limestone of Bolland. 



6 ACTINOCRINUS {Amphoracrinus?) OLLA (M^Coy). Profile of specimen, natural size, from the carbo- 



niferous limestone of Derbyshire. 



7 CODONASTER ACUTUS (M^Coy). Profile of specimen, natural size, from the carboniferous limestone of 



Derbyshire. 



8 CODONASTER TRILOBATUS (M^Coy). Profile of specimen, natural size, from the carboniferous limestone 



of Derbyshire. 



8 a End view of truncated summit of ditto, magnified. 



9 PENTRE JUTES CAMPANULATUS (JPCoy). Magnified four diameters, from the carboniferous limestone 



of Derbyshire ; the line shews the natural size. 



10 GRIFFITHIDES MESO-TUBERCULATUS (M'=Coy). Part of cephalic shield, natural size, from black beds 



overlying the main carboniferous limestone of Derbyshire. 



11 Pygidium of ditto, natural size. 



11 a Two pseudo-segments of pygidium, magnified. 



12 PENTAMERUS CARBONARIUS (JPCoy). Natural size, front view, shewing the very small sinus in the 



front margin of a specimen, in which the mesial fold is nearly simple ; from the carboniferous limestone of 

 Kendal. 



13 Fragment of one side of the beak of receiving valve, shewing the width of the mesial septum ; on the left- 

 hand side, one of the concave diverging halves in the middle, and part of the cardinal area on the right-hand side. 

 The apex of the beak being downward. 



14 Longitudinal fracture of large specimen, shevsdng the great length of the mesial septum, and portion of the 



divaricating part thereof in the receiving valve, and one of the short narrow septa of the entering valve. 



15 Entering valve of specimen, with much branched ridges, and much incurved, shghtly oblique beak to the 



receiving valve. 



15 a Portions of two of the ridges, magnified to shew the minute pustulation of the surface. 



16 Variety with very high cardinal area, and only slightly incurved beak to the receiving valve, and having the 



lateral ridges simple. 



17 Profile of variety, with very gibbous entering valve, and very much incurved beak to the receiving valve. 



18 Transverse section of both valves, shewing below a section of the two small septa of the entering valve, 



and above, the broad mesial septum, with portions of the divaricating parts. 



19 HEMITHYRIS HETEROPTYCHA (M'^Coy). From the carboniferous limestone of Derbyshire; front view, 



natural size ; (the two mesial ridges should be slightly wider, and the lateral ones slightly narrower). 

 19 a Receiving valve. 



19 h Profile of ditto (the top of the sinus should incMne slightly more towards the beak, and the middle be- 



hind the front edge should be more elevated from the front, and flattened in the middle). 



] 9 c View of entering valve of ditto, magnified two diameters, to shew the difference in character between the 



mesial and lateral ridges. 



20 CAMEROPHORIA LATICLIVA (IVrCoy). Extremely large specimen, from the carboniferous limestone of 



Derbyshire, shewing the narrow straight sides, and extremely wide defined mesial hollow of the receiving valve, 

 natural size, shewing one short, unusual additional ridge ia the sinus, and one or two at the side margins, 

 from the extreme age. 



• Since the text was printed IM. de Koninck informs me that he has got perfect specimens of the typical Cupressocrinus from the Eifel, 

 and finds that there are no interradial plates ; so that the appearance I allude to in the text in our Eifel specimen must have beer, produced by 

 fracture, and the two species above-named must be considered as forming a peculiar section of Poteriocrinus, rather than of Cupressocnnu: 

 The specific name of C. impressus must be changed to Poterincrinus ennvat^is (M'Coy), as there is already a P. impresstis. 



