The theory of third-order aberrations of the system rotary symmetrical aspheric thin lenses and the relations for calculation of the shape rotary symmetrical aspheric spectacle lenses with zero astigmatism are stated. A comparison the possibility of the aspheric and spherical spectacle lenses is presented. and Je uvedena teorie aberací 3. řádu soustavy tenkých rotačně symetrických asférických čoček. Jsou odvozeny vztahy pro výpočet tvaru rotačně symetrické asférické brýlové čočky s korigovaným astigmatismem a je provedeno srovnání se sférickou brýlovou čočkou.
Notopronocephalus peekayi gen. et sp. n. is described from the intestine of Elseya latistemum Gray, 1867, E. dentata (Gray, 1863) and Emydura signala Ahi, 1932 from rivers in Queensland. The new genus is distinguished by the absence of ventral glands, simple (neither diverticulate nor sinuous) caeca terminating at the anterior margin of the testes, excretory arms not uniting in forebody, single ovary, two opposite testes close to the posterior end of the body, intracaecal genital pore, vitelline follicles anterior to the testes, cirrus-sac orientated obliquely and not divided into two portions, and the uterus intracaecal. This is the first pronocephalid to be described from an Australian freshwater turtle and the first from the family Chelidae.