6 
1897, 1904) held ‘Lutra’ minor to be a subspecies of Potamotherium 
valletoni while Pohle (1920), Haupt (1935), and Savage (1957) 
simply placed it in the synonymy of that species. Schlosser (1888: 
123) expressly denied the specific status of “Lutra’ minor (“Ebenso 
ist auch Stephanodon minor H. v. Meyer auf keinen Fall als besondere 
Art zu betrachten’), including it in Potamotherium valletoni, but 
later (1890) he quoted it as a separate species of Potamotherium. 
The synonymy list of ‘Lutra’ minor Lydekker, 1885 includes the 
following names: 
1885  Lutra minor [or] [Lutra] minor Lydekker: xxi, 195, 266. 
1885  Stephanodon minor, Lydekker: 195, 267. 
1885. [Lutra valetoni| minor; Trouessart: 47. 
1888  Stephanodon minor; Schlosser: 123. 
1890  [Potamotherium] minor; Schlosser: 82. 
1897 [Potamotherium Valetoni] minor, Trouessatt: 281. 
1904 [Potamotherium valetoni] minor, Trouessart: 212. 
1920 Stephanodon minor [or] [Stephanodon] minor; Pohle: 16— 
Wy 223s 
1935 Stephanodon minor; Haupt: 38. 
1957 Potamotherium minor; Savage: 155. 
DESCRIPTION OF THE HOLOTYPE. The holotype, by monotypy, of 
‘Lutra’ minor Lydekker, 1885 is BMNH 25449, a fragment of a left 
dentary with partially eroded P, and M, (Fig. 2, Tables 1-3). The 
side-walls of the preserved fragment of body in the holotype dentary 
are convex in cross-section, excepting the ventral part of the medial 
wall where the surface of the dentary bone is somewhat depressed 
along the ventral border. The alveoli for P,-M, are arranged one 
behind the other and closely spaced. P, and M, slightly overlap each 
other and have pairs of alveoli. Only the anterior part of the M, 
alveolus is preserved; judging from this preservation, the alveolus 
was single and anteroposteriorly elongated. The masseteric fossa 
extends anteriorly to the level of the alveolus for M.,,. 
The morphological patterns of P, and M, are congruent with those 
of the corresponding teeth in the type specimen of *Plesictis'croizett, 
with the exception of the following differences concerning M.;: in the 
holotype of ‘Lutra’ minor the lingual ridge of the paraconid is 
shorter; the lingual contour of the metaconid is slightly concave; the 
metaconid is somewhat deflected posteriad, making its posterior 
contour slightly concave when viewed from the lingual side; there is 
no crest on the anterior face of the metaconid, so that the anterior 
slope of this cusp is widely rounded and blunt; and, finally, no 
elevation could be detected on the posterior wall of the talonid. The 
crowns of P, and M, are generally less worn in the holotype of 
‘Lutra’ minor than those of the type specimen of *Plesictis’ croizeti. 
TYPE LOCALITY. The old vertebrate register at NHM reports the 
holotype of ‘Lutra’ minor as having been collected in ‘Mayence’ 
(=Mainz). Lydekker (1885: 195) described it as coming ‘from the 
Lower Miocene of Mombach, near Mayence’ (now Mainz- 
Mombach), perhaps on the basis of an original, but now missing, 
specimen label. Lydekker’s attribution is consistent with that on the 
label accompanying the holotype at present. Schlosser (1890), who 
knew both Lydekker’s (1885) catalogue and H. von Meyer’s unpub- 
lished drawings of carnivoran remains from Mainz-Weisenau (as 
seen from Schlosser 1887: 4, 6), referred ‘Lutra’ minor (his Potamo- 
therium minor) to ‘Mainz (Weissenau)’ (=Mainz-Weisenau). No 
evidence exists, however, to suggest that Schlosser’s assignment 
concerned specimen(s) other than the holotype and, moreover, none 
of the copies of von Meyer’s drawings preserved in NMB represents 
the type specimen of ‘Lutra’ minor. Consequently, we conclude that 
Schlosser’s Potamotherium minor pertained to the holotype of “Lutra’ 
minor, and hence its referral to the locality Mainz-Weisenau resulted 
from confusion. 
M. WOLSAN AND M. MORLO | 
Table 1 Mandible measurements (in mm) of the holotype of “Plesictis’ 
croizeti Pomel, 1847 and ‘Plesictis’ gracilis Pomel, 1853 (BMNH 
26702), and the holotype of ‘Lutra’ minor Lydekker, 1885 (BMNH 
25449). 
BMNH BMNH 
26702 25449 
Distance between posterior-most points of C, 
and M., alveolar rims B19 - 
Greatest distance between alveolar rims for M, and M, 11.6 - 
Length of P, alveolus (greatest diameter of P, 
alveolar rim) 2.0e —- 
Width of P, alveolus (least diameter of P, 
alveolar rim) 1.0 - ; 
| 
| 
| 
| 
| 
Length of P, alveoli (greatest distance between rims 
of anterior and posterior alveoli for P,) 4.6 - ; 
Width of P, alveoli (least distance from line connecting : 
lingual-most points of P, alveolar rims to buccal- 
most point of these rims) ep) = 
Length of P, alveoli (greatest distance between rims 
of anterior and posterior alveoli for P,) 60) = 
Length of P, alveoli (greatest distance between rims 
of anterior and posterior alveoli for P,) q-3} 6.62 
Length of M, alveoli (greatest distance between rims 
of anterior and posterior alveoli for M,) 8.6 8.5 
Length of M, alveolus (greatest diameter of M, 
alveolar rim). ‘ 2.6e - 
Width of M, alveolus (least diameter of M, 
alveolar rim) PIgp - 
Greatest horizontal distance between lateral and 
medial walls of dentary below M, perpendicular to 
long axis of dentary 5.6 5.8 
Least distance from alveolar border of dentary 
between P, and P, to its ventral border, measured 
on medial side 93 = 
Least distance from alveolar border of dentary 
between M_ and M, to its ventral border, measured 
on medial side 10.5 WE7/ 
a 
‘e’ indicates an estimated value. 
Table 2 Measurements (in mm) of premolar teeth in the holotype of 
‘Plesictis’ croizeti Pomel, 1847 and ‘Plesictis’ gracilis Pomel, 1853 
(BMNH 26702), and the holotype of ‘Lutra’ minor Lydekker, 1885 
(BMNH 25449). 
BMNH BMNH 
26702 25449 
Length of P, (from anterior-most to posterior-most 
points of crown) 6.2 = 
Width of P, (greatest distance between buccal and 
lingual borders of crown perpendicular to antero- 
posterior length of tooth) 2.8+ = 
Height of P, (least distance from occlusal-most point 
of tooth to basal margin of crown, measured on 
buccal side) 3.8 - 
Length of P, (from anterior-most to posterior-most 
points of crown) UA gal 
Width of P, (greatest distance between buccal and 
lingual borders of crown perpendicular to antero- 
posterior length of tooth) 333) 3.4 
Height of P, (least distance from occlusal-most point 
of tooth to basal margin of crown, measured on 
buccal side) 
‘4? indicates a minimum measurement on an incomplete structure, “e’ indicates an 
estimated value. 
