140 The Ottawa Naturalist. [Feb. 



but was not used in any definite sense until Matthew's publica- 

 tion. 



The case of Cryptolithus versus Trinucleus has been reviewed 

 recently by Foerste, 11 who comes to the only possible conclusion, 

 which is, that the use of Trinucleus is unjustified. The present 

 habit of dating Trinucleus back to Llhwydd (1698) can not be 

 upheld, as he was a pre-Linnaean writer, and his use of Trinu- 

 cleum was not at all in a modern generic sense. Murchison was 

 the first describer of Trinucleus, which thus dates from 1839 

 (Silurian System). In 1832, two names were given to the 

 trilobite which we usually call Trinucleus, Cryptolithus by Green 

 in the monthly "American Journal of Geology and Natural 

 Science," and Nuttainia by Eaton in the second edition of his 

 text book. Both names appeared in the latter half of the same 

 year, and it is not absolutely clear which appeared first. Dr. 

 Foerste has stated the circumstances in detail, and shows that 

 the evidence rather favours Green's name. Green certainly 

 claimed priority, and we have no evidence that Eaton insisted 

 that his name was published first. It is worthy of note that 

 Cryptolithus was adopted by Bronn, Goldfuss, Emmrich, and 

 Angelin, while Eaton's name was never again used by anyone for 

 this genus. 



In cases of priority, where the same species was not used 

 as the type by both authors, it is of course necessary to proceed 

 with caution, for further investigation may show that the two 

 tvpe-species reahy belong to different genera, as has proven 

 the case with Cheirtirus and Ceraurus, genera which have long 

 been considered identical. In the present case the two types 

 seem to be congeneric. Green's Cryptolithus tessellatus was 

 founded on a specimen found in the shale at Waterford, New 

 York. Murchison's first species was Trinucleus caractaci, 

 which must be taken as the type of Trinucleus. Green's species 

 differs from Murchison's in lacking the genal spines, and in 

 having three instead of six rows of punctures on the border. 

 The presence or absence of the genal spines is a condition of 

 preservation, as the genal spines are on the free cheeks, and the 

 number of rows of punctures varies within the limits of a single 

 species, so it 'seems unlikely that these two species will ever 

 require separate generic names. 



The Ogygia, Ogygites, Ogygiocaris tangle is complicated but 

 yields a satisfactory solution, as I have briefly shown recently."" 

 Ogygia was proposed by Brongniart, 11 who cited two species. 



9 Bull. Denison Univ., p. 78, 1910. 



10 Trans. Roy. Soc. Canada, ser. 3, vol. 5, sect. 4, p. 116, 1912. 



11 Histoire Naturelle des Crustaces Fossilcs, p. 7, 1822. 



