Finding the citation of an original species authority for any species can be a bit daunting. But there are some great tools to help you identify the current accepted scientific name, the original scientific name, and the work in which it was cited. Additionally, thanks to digital archives, you may actually be able to view the original publication.
Wikipedia is a useful tool for looking up species. Just remember, it is a crowd-sourced resource, so its accuracy may not be 100%. Use it to find the scientific name and potentially the author of the original species description.
Eschmeyer's Catalog of Fishes
An authoritative reference for taxonomic fish names, featuring a searchable on-line database. This resource is particularly useful for references to published works about a fish ranging from the original description to taxonomic reclassification.
World Register of Marine Species (WoRMS)
WoRMS is a comprehensive database of marine taxonomic information. In particular, it is useful for viewing changes in taxonomic classification and nomenclature over time. You can often find the original species name as well as the current accepted species name.
Integrated Taxonomic Information System
A basic search tool with authoritative taxonomic information records.
Biodiversity Heritage Library
A vast searchable digital archive of biology material. Includes some Linnaeus works.
4. Finding the description in the scanned book can be a challenge. The search tools don't always work as you might expect. Sometimes searching for the binomial name doesn't work because the genus and species are not listed as a phrase (see below). Try searching for the species name only. Other tips to find the description include looking for a table of contents or index. After a bit of a hunt for ocellata in the Perca (genus) category of Pices (Fishes), we find the entry on page 483.
I look forward to helping you with your research needs. Please contact me or make an appointment!