Genomax already answered, but here is also a mysql command you can use if you don't want to download the entire hgcentral database dump:
$ mysql -h genome-mysql.soe.ucsc.edu -u genome -e "select name, scientificName from dbDb limit 5" hgcentral
+---------+-------------------------------------+
| name | scientificName |
+---------+-------------------------------------+
| hg38 | Homo sapiens |
| balAcu1 | Balaenoptera acutorostrata scammoni |
| calMil1 | Callorhinchus milii |
| rn6 | Rattus norvegicus |
| sorAra2 | Sorex araneus |
+---------+-------------------------------------+
If you have further questions about UCSC data or tools feel free to send your question to one of the below mailing lists:
- General questions: genome@soe.ucsc.edu
- Questions involving private data: genome-www@soe.ucsc.edu
- Questions involving mirror sites: genome-mirror@ose.ucsc.edu
ChrisL from the UCSC Genome Browser