| HYBRID | Interspecies mixing sometimes designated with an "x" in the scientific name |
| TICTACTOETACTIC | Starting with an X in the corner, say? |
| USER | Kind of error sometimes designated PICNIC (4) |
| PORGYANDBASS | Film about an interspecies fish relationship? |
| ATALANTA | Mythological Greek huntress whose name is recalled in the scientific name for the red admiral (8) |
| GULO | Word in the scientific name for wolverines, from the Latin for "glutton" |
| MISMARK | Place an "X" in the wrong spot on, say |
| ROSEUM | Latin word used in the scientific names of plants such as the rosy hyacinth-orchid and the rose geranium (6) |
| NEPTUNE | Named after the Roman god of the sea, hence designated with the symbol of a trident, the outermost planet of our solar system (7) |
| MARK | A boundary indicator; a symbol such as an X in place of a signature; the start line in a race; or, a target (4) |
| CHRIST | His name is represented by the X in the clue for 117A |
| RUMINANT | What is the scientific name for an animal that chews the cud? (8) |
| KAYAK | Canoe designated with the letter K in Olympic events (5) |
| BOTANIST | An expert in the scientific study of plants (8) |
| LABORATORY | Split work with speechmaking in the scientific establishment (10) |
| STEWART | Patrick, English actor who from the year 2000 played Professor X in the X-Men film series (7) |
| WORMS | Invertebrate animals having soft, long bodies; a new cave variety was found in the Bay of Alcudia, Mallorca last year and given the scientific name of Pollentia perezi (5) |
| ASP | Snake with the scientific name Naja haje |
| ARROW | Hidden symbol between the "E" and "x" in the FedEx logo |
| ATHENA | The scientific name of the little owl is ___ noctua (6) |
