THORACICA. 



217 



observations of Darwin (No. 40), Pagbnstecher (No. 58), and 

 Claus (Nos. 39 and 8). 



The larva attaches itself firmly with the sucking discs found on 

 the first antennae and by means of a sticky fluid secreted by the 

 ■cement-gland. At first the whole of the ventral surface is in contact 

 with and parallel to the surface of attachment (Fig. 106 ^ and B). 

 The changes Avhich first attract attention are certain processes of 

 growth by means of which different parts of the body approach the 

 final shape. For example, the mouth-parts at the top of the buccal 

 cone, which until now were very rudimentary, become distinctly 



-K- 



i-f ^'o Vdy / 



Fig. 106.— Diagrammatic illustration of the metamorphoses of Lepas. A, Cypris-VCiia stage. 

 B, attached pupa. C, young Lepas stage, still surrounded by the loosened Cypris shell (s). 

 a', first antenna; ah, abdomen; c, carina; d, intestine; to, mouth; o, unpaired eye; pa, 

 paired eye ; rf, thoracic limbs ; s, Cypris shell ; sc, scutum ; t, tcrgum ; x, reflection of the 

 dorsal integument ; y, ventral fold. 



developed ; in the Lepadidae the principal feature in this process is 

 the great increase in size of the upper lip. The thoracic limbs also 

 elongate and become (Fig. 106 B) the rudiments of the tendril-like 

 feet ()/). All these parts develop under the sonaewhat loose Cypris 

 cuticle. The long tendril-like feet naturally have not the room 

 necessary for development in the short envelope of the thoracic 

 limbs of the Cypris stage, and therefore become much curved, and 

 even press back into the thorax (Fig. 105), The abdomen degenerates 

 almost completely, while from its base (genital segment) the unpaired 

 penis projects as an outgrowth. 



