. Chordate morphology. Morphology (Animals); Chordata. anterior lateral cartilage' styloid cartilage apical cartilage posterior lateral cartiloge spinous cartilage NNv^velor cartilage. copular cartilage â piston cartilage Figure 5-27. Stages in the development of the head skeleton of the lamprey. A, B, lateral and ventral views of 8 to lO-mm larva; C, lateral view of early metamorphic larva; D, lateral view of late metamorphic larva; E and F, lateral views of adult head and tongue elements. (After Johnels, 1948) connective tissue to the ventral surface of this commissure. From the anterolatera
. Chordate morphology. Morphology (Animals); Chordata. anterior lateral cartilage' styloid cartilage apical cartilage posterior lateral cartiloge spinous cartilage NNv^velor cartilage. copular cartilage â piston cartilage Figure 5-27. Stages in the development of the head skeleton of the lamprey. A, B, lateral and ventral views of 8 to lO-mm larva; C, lateral view of early metamorphic larva; D, lateral view of late metamorphic larva; E and F, lateral views of adult head and tongue elements. (After Johnels, 1948) connective tissue to the ventral surface of this commissure. From the anterolateral angles of the commissure a cornual process extends out and forward. Attached to the inner aspect of the subocular visceral plate by ligaments is a complex of several cartilaginous rods which extend back and medially into the velum. The velum lies between the opening of the nasohypophyseal duct into the mouth and the pharynx; it extends backward into the pharynx. Its margins roll and unroll so as to pump water from the mouth cavity into the pharynx. The nasal sac and nasal duct are enclosed in a fenes- trated capsule and a series of loops. Below these is a laterally compressed rod forking anteriorly into two tentacular rods; this is the subnasal cartilage. The posterior end of the sub- nasal cartilage lies just anterior to the tip of the hypophyseal cartilage. The latter underlies the hypophyseal duct and, about midway along its length, attaches to the trabecula of either side. Below the endocranium is an extensive tongue skeleton. This is joined to the neurocranium through the external division of the first branchial arch. This arch attaches to the posterolateral angle of the median lingual cartilage. Ante- rior to this plate are two pairs of anterior lingual cartilages âlateral and medial. The medial pair is fused anteriorly. The anterior margins of the lateral plates give rise to rods which extend anteriorly. These divide distally into dorsal (nasal) and ventral (oral) te
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