180 
THE GEOLOGIST. 
the same horizontal plane, whilst in the Poteriocrinus there are two which extend 
beyond the others, as I have already remarked, in 1852, in my "Recherches sur les 
Crinoides " (p. 85). The anal plates are small, and a trifle less bowed than the 
others. The surface of all these plates is perfectly smooth. All the other parts 
are unknown to me ; but the articulation of the base with the stem demoastrates 
the latter to have been very slight. Dimensions. — The length of the calix is only 
Gmin^ its diameter 1G""°, that of the base 5"'™, that of the stem I Smm. 
A^ffiriitics and Differences. — This species resembles very mucb. my 
Hydreiouocrinus (Poteriocrinus) ilaecoyanus, from which, however, it. 
will not be difficult to distinguish it, by reason of the very decided 
convexity of the different plates of the calix, and the feeble dimensions 
of the stem. 
Position and Locality. — This species has been discovered in the 
environs of Glasgow, in a black schist, subordinate to the carboniferous 
limestone with Productus giganteus and Spirifer bisulcatus. I owe 
the knowledge of it to Mr. Salter, Palaeontologist to the Geological 
Survey of Great Britain, so well known for a great number of impor- 
tant researches. 
Explanation of figures. — PI. IV : — 
Fig. 6. — Calix, seen from the side of the base, slightly enlarged. In the collec- 
tion of the Geological Survey at London. 
Fig. 7. — The same, seen in profile, of natural size. 
The following is the description of a third crinoid, very remarkable 
for the globular form of its calix, which I dare not place definitelj'^ 
amongst the Hydreionocrini, because it differs in its general character, 
and because the upper parts of the bulb are unknown to me. I am not 
more able to class it, in a certain manner, among the Poteriocrini, as it 
differs from most of them in the form and perfectly horizontal position 
of its radial plates, which are all, as in the true Hydreiouocrinus, placed 
on the same plane. 
3. Hydrcionocrinus ? globularis. De Koninclc. PL IV., fig. 1 — 4. 
The Calix of this pretty species is of ordinary size, and of sub-sphoeroidal form, 
slightly elongated at its base. Its surface is perfectly smooth, and the sutures of 
the various i)lates scarcely perceptible, and not indicated by any depres.sion or 
groove. The basal plates are all nearly of the same form, producing by their union 
a small star with five well-marked rays. The articulation of the stem is situated 
in the hollow of a small, round, shallow ditch. The sub-radial plates are very 
large and slightly, also, broader than long. Four of them have a tolerably regular 
hexagonal form ; the fifth has soveu sides, of which one is welded to the anal plates. 
The first radial plates, those only which are known to me, offer three different forms, 
the three most distant from the anal side are similar one to another ; they ai-e 
pentagonal, and one a little broader than long. Of the two last, that which is placed 
