They are called "cerebral" consonants if I remember aright.

Yes, the Sanskrit term is mūrdhanya 'cerebral' (< mūrdhan 'head', cf. Old English molda 'top of the head' link). They are called retroflex consonants in Western phonology, because the tip of the tongue is turned back a bit to touch the palate or just behind the alveolar ridge. The dental (in Sanskrit called dantya) series is more like Romance dentals, with the tongue touching the back of the upper row of teeth, while the English dentals (e.g., t, d) are really alveolar consonants with the tongue touching the alveolar ridge above the teeth. It's interesting that most English loanwords in Hindi (and other north Indian languages) use retroflex phones to transliterate English alveolars rather than dental ones (e.g., इसटेषन isṭeshan 'station').

Ceci n'est pas un seing.