SOCNOP^A GEANDIS. 315 



Genus SOCNOP^A, Stromer. 

 [Neues Jahrb. 1904, vol. i. (Abhandlungen) p. 6.] 



This genus was founded by Stromer for the reception of a single species of large 

 Siluroid from the Qasr-el-Sagha beds. The basioccipital is said to bear paired 

 processes for union with the post -temporal, as in Bagrus, to which this form is 

 probably nearly related. 



Socnopsea grandis, Stromer. 



1904. Socnopcea grandis, Ernst Stromer, Neues Jahrb. vol. i. (Abhandlungen) pp. 6-7, pi. i. 

 fig. 3. 



Ti/pe Specimen. — An imperfect skull ; Palseontological Museum, Munich. 



This species seems to have attained a very large size. The sculpturing of the skull- 

 roof differs widely from that of Fajumia, and consists of numerous small tubercles 

 arranged in longitudinal lines, there being no rows of specially enlarged tubercles at 

 the sides of the median depression. This latter is long and sharply defined ; into it 

 there open two fontanelles, one near its anterior end, the other near the middle. The 

 supraoccipital region projects considerably behind the rest of the skull. 



Form. & Log. — Qasr-el-Sagha beds (Middle Eocene) : north of Birket-el-Qurun. 



C. 10199. Skull and large part of the skeleton o£ a very large individual. The principal parts 

 preserved are : — (1) Skull, somewhat incomplete towards the outer angles o£ its 

 anterior end, showing the characteristic sculpture ; (2) portions of the mandible and 

 byomandibular ; (3) part o£ the vertebral column, including the anterior complex 

 vertebra and a series of about nineteen others ; (4) the interneural plate with the 

 dorsal spine ; (5) portions of the two halves of the shoulder-girdle with the pectoral 

 spine. This specimen shows that these Eocene Siluroids attained a large size, the skull 

 being about 65 cm, long, about 21 cm. wide posteriorly, and 32 cm. wide in front; the 

 length from the basioccipital to the tip of snout is 56"5 cm. The complex vertebra 

 is about 15 cm. in length, and the vertical diameter of the anterior end of its centrum 

 about 5"7 cm. The arrow-head- shaped interneural plate is large, its length in the 

 mid-dorsal line being 11 cm., length to posterior angles 17 cm., greatest width upwards 

 of 12 cm. Its dorsal surface is covered with an ornamentation of rounded tubercles 

 arranged more or less in lines, and rather larger and more prominent than those on the 

 skull-roof. The posterior notch is occupied by the small supporting spine of the usual 

 form, and behind this by the large dorsal spine ; this was probably about 20 cm. long 

 and curved backwards ; it seems to have had a tuberculate anterior border and sides 

 marked by fine irregular ridges. The width of the base of this spine from side to side 

 is 4"3 cm., the width of its middle region from before backwards about 2"5 cm. The 



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