Dear Olexander 

you may see the Bornbush (2008) in link below:

http://onlinelibrary.wiley.com/doi/10.1111/j.1096-3642.1995.tb02322.x/abstract

and

http://fishbase.org/physiology/MorphDataSummary.php?genusname=Silurus&speciesname=soldatovi&autoctr=9259

eventually I think the link below is very useful for you

http://www.wdc-jp.biz/pdf_store/isj/publication/pdf/36/362/36201-2.pdf

Regards

Massih

You may wish to consult the following papers on the taxonomy of recent species of Silurus, which also discuss the major skeleton elements and their taxonomic significance:

Kobayakawa, M. 1989. Systematic revision of the catfish genus Silurus, with description of a new species from Thailand and Burma. Japanese Journal of Ichthyology v. 36 (no. 2): 155-186.

Kobayakawa, M. 1992. Comparative morphology and development of bony elements in the head region in three species of Japanese catfishes (Silurus: Siluridae; Siluriformes). Japanese Journal of Ichthyology v. 39 (no. 1): 25-36.

You may consult this papers too:

Comparison of morphological and anatomical characters in two catfish species, Silurus triostegus Heckel, 1843 and Silurus glanis L., 1758 (Siluridae, Siluriformes)

E Ünlü, D Değer, T Cicek - North-Western Journal of Zoology, 2012

and

Diogo, R., Oliveira, C., & Chardon, M. (2001). On the osteology and myology of catfish pectoral girdle, with a reflection on catfish (Teleostei: Siluriformes) plesiomorphies. Journal of Morphology, 249(2), 100–25

Dear colleagues! Many thanks to you for your helpful suggestions!