244 
SIREN 0IDEI. 
Type. Left palatine dental plate ; Museum, University of Liege. 
A species apparently larger than P. insignis. Palatine dental 
plates with not less than five widel} r -spaced, radiating, coronal ridges, 
coarsely crenulated. 
Form. Sf Loc. Upper Devonian : Belgium. 
43805. Plaster cast of type sjiecimen. 
Presented by Prof. P. J. Van Beneden , 1872. 
Palsedaphus lesleyi (Newberry). 
1875. Heliodus lesleyi , J. S. Newberry, Rep. Geol. Surv. Ohio, vol. ii. 
pt. ii. p. 64, pi. lviii. fig. 18. 
1889. Heliodus lesleyi , J. S. Newberry, Palaeoz. Fishes N. America 
(Mon. U.S. GeoL Surv. no. xvi.), p. 86, pi. xviii. fig. 3. 
Type. Upper dental plate; Columbia College, New York. 
A species much smaller than either of the preceding, known only 
by a single example of the upper dental plate; characterized by 
eight coarsely crenulated or tuberculated coronal ridges, symmetri¬ 
cally radiating, and diminishing in size anteriorly and. posteriorly. 
This dental plate is regarded by Newberry as azygous, repre¬ 
senting the ordinary pair of palatine plates, and is thus made the 
type of a distinct genus, Heliodus. The present writer considers 
that the specimen is a normal right or left palatine. 
Form. Sf Loc. Upper Chemung Group : North Pennsylvania. 
Not represented in the Collection. 
A portion apparently of a very large dental plate, much resem¬ 
bling the palatine of Pcdcedaphus, is described as Archceonectes per- 
tusus , H. von Meyer, Pakeontogr. vol. vii. (4859), p. 12, pi. ii. figs. 
1, 2. The following is the type specimen :— 
33596. Portion of dental plate with parts of four coronal ridges, 
and showing a large transversely oval foramen near the 
inner border; Devonian, Gerolstein. The specimen is 
regarded as the palatal region of a Dipnoan, wanting the 
dental plates, by A. Fritsch, Fauna der Gaskohle, vol. ii. 
(1888), p. 90, woodc. fig. 170. Purchased , 1859. 
Also probably closely allied to Palsedaphus is a Dipnoan fish from 
the Devonian of the Government of Orel, Russia, of which the frag¬ 
mentary mandible was described under the name of Holodus Tcipri- 
janoivi by C. H. Pander, Ctenodipt. devon. Syst. (1858), p. 38, pi. vi. 
figs. 1-14. In the original descrijition the specimen is regarded as 
the anterior portion of the skull, and this determination is considered 
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