Allen and Greenough's New Latin Grammar, section 4

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4.

Consonants are further classified as in the following table:

Labials Dentals Palatals
Mutes: Voiced (mediae) b d g
Voiceless (tenués) p t c (k,q)
Aspirates ph th ch
Nasals m n n (before c, g, q)
Liquids l, r Fricatives (Spirants)
Sibilants s, z Semivowels

Double consonants are x (=cs) and z (=dz); h is merely a breathing.
1. Mutes are pronounced by blocking entirely, for an instant, the passage of the breath through the mouth, and then allowing it to escape with an explosion (distinctly heard before a following vowel). Between the explosion and the vowel there may be a slight puff of breath (h), as in the Aspirates (ph, th, ch).[2][The aspirates are almost wholly confined to words borrowed from the Greek. In early Latin such borrowed sounds lost their aspiration and became simply p, t, c.]
2. Labials are pronounced with the lips, or lips and teeth.
3. Dentals (sometimes called Linguals) are pronounced with the tip of the tongue touching or almost touching the upper front teeth.
4. Palatals are pronounced with a part of the upper surface of the tongue toughing or approaching the palate.[3][Palatals are often classed as (1) velars, pronounced with the tongue touching or rising toward the soft palate (in the back of the mouth), and (2) palatals, in which the tongue touches or rises toward the hard palate (farther forward in the mouth). Compare the initial consonants in key and cool, whispering the two words, and it will be observed that before e and i the k is sounded farther forward in the mouth than before a, o or u.]
5. Fricatives (or Spirants) are consonants in which the breath passes continuously through the mouth with audible friction.
6. Nasals are like voiced mutes, except that the mouth remains closed and the breath passes through the nose.

	Labials	Dentals	Palatals
Mutes: Voiced (mediae)	b	d	g
Voiceless (tenués)	p	t	c (k,q)
Aspirates	ph	th	ch
Nasals	m	n	n (before c, g, q)
Liquids		l, r	Fricatives (Spirants)
Sibilants		s, z	Semivowels
Double consonants are x (=cs) and z (=dz); h is merely a breathing. 1. Mutes are pronounced by blocking entirely, for an instant, the passage of the breath through the mouth, and then allowing it to escape with an explosion (distinctly heard before a following vowel). Between the explosion and the vowel there may be a slight puff of breath (h), as in the Aspirates (ph, th, ch).[2][The aspirates are almost wholly confined to words borrowed from the Greek. In early Latin such borrowed sounds lost their aspiration and became simply p, t, c.] 2. Labials are pronounced with the lips, or lips and teeth. 3. Dentals (sometimes called Linguals) are pronounced with the tip of the tongue touching or almost touching the upper front teeth. 4. Palatals are pronounced with a part of the upper surface of the tongue toughing or approaching the palate.[3][Palatals are often classed as (1) velars, pronounced with the tongue touching or rising toward the soft palate (in the back of the mouth), and (2) palatals, in which the tongue touches or rises toward the hard palate (farther forward in the mouth). Compare the initial consonants in key and cool, whispering the two words, and it will be observed that before e and i the k is sounded farther forward in the mouth than before a, o or u.] 5. Fricatives (or Spirants) are consonants in which the breath passes continuously through the mouth with audible friction. 6. Nasals are like voiced mutes, except that the mouth remains closed and the breath passes through the nose.