ExporaMed logoStealthy Mountain View, Calif.-based ExploraMed NC4 has raised $18.5 million of an expected $20 million first funding round, I’m told. The medical-device startup doesn’t have a Web site, and doesn’t even seem to have its own address yet.

Instead, ExploraMed NC4 — the name is a placeholder intended to obscure the startup’s strategy — is still housed at ExploraMed, a medical-device incubator backed by New Enterprise Associates, among others. ExploraMed was founded in 1995 by Joshua Makower, an NEA venture partner and a Stanford consulting professor who also co-directs the university’s Biomedical Technology Innovation Program.

Makower confirmed the fundraising, but declined to say what NC4 will be doing. “I love to talk about my companies, but I’ve found there’s virtue in keeping things secret as long as possible from competitors who are just dying to know what we’re up to,” he said. “I’ve learned from experience that if they can get a whiff of what we’re doing, they’ll just copy it.” Makower is not the startup’s CEO, and says ExploraMed will announce NC4’s leader “at the right time.”

Investors in the NC4 round include NEA, Morgenthaler Partners and the Makower Family Trust. Makower said the company is still corralling individual investors who’ve expressed interest in contributing the remaining $1.5 million for the round.

ExploraMed has so far launched five device makers, several of which we’ve covered here at VentureBeat LifeScience. Its most recent companies include Vibrynt, a stealthy device maker that raised $16 million in Aug. 2007, and NeoTract, a Pleasanton, Calif., developer of devices for non-cancerous prostate growths, which raised a total of $21.4 million in its first round.

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