DESCRIPTION OF PLATE, 22. 657 



Fig. 7, small portion of the external membrane, showing the star- 

 shaped, hard, projecting points of chitine ; but they are 

 here placed too closely together. 



8, front view of mouth, greatly enlarged, and with the gnathites 



rather unnaturally separated from each other; h, the first 

 pair of cirri; in front, the outer maxillae appear like a 

 bi-lobed lower lip ; the inner maxillae (with their singular 

 membranous swelling behind, "see fig. 15), can be dis- 

 tinguished by their long apodemes or horny imbedded 

 bars ; behind are seen the one-toothed mandibles, with a 

 swelling behind, probably representing the palpi ; all 

 above the mandibles consists of the immensely developed 

 labrum, with the foreshortened ends of the row of long 

 hairs on each side : the fold, or articulation, separating 

 the mouth and body, is seen crossing above the basal 

 ends of the apodemes of the maxillae. 



9, Lateral view of the coriaceous button or cushion, c', on one corner 



of the upper segment, b, of the pedicel of the sixth cirrus ; 

 c, being the lower part of the lower segment of. the one 

 ramus of this same cirrus : the hooked hairs are rather 

 distorted. 



10, The same, viewed from the inner side. 



1 1, Lateral view of the labrum, with the mandible, m t attached to 



it, which latter, from overhanging the oesophagus, shows the 

 position of the mouth ; h h, is the first cirrus on the near 

 side; b, is the medial crest of labrum, on the side of which 

 extends a long row of hairs ; a a a, delicate membrane 

 of side of body, attached to the margins of the labrum. 



12, Diagram showing the probable manner in which the young 



Alcippe bores into the shell of molluscs; a, pupa attached 

 by the antennae to the outer surface of shell ; b, outline of 

 young Alcippe soon after its metamorphosis ; the anterior 

 or lower end has increased considerably in length, so as to 

 project beyond the point whence the antennae rise, and it 

 has now penetrated the shell, being attached to the roof 

 of its incipient chamber by its horny disc, represented by 

 a thick black line ; c, is the Alcippe after further growth, 

 when it has succeeded in burying itself; the horny disc is 

 now attached parallel to .the surface of the shell ; the 

 horny disc of its former state, now lines the narrow end 

 of the slit-like orifice leading into the shellv chamber : the 

 above changes in position are supposed to have been 

 effected quite gradually. The diagram, c, I may add, 

 represents the position of the Alcippe for the rest of its 

 life, the chamber being added to at both ends, sides, and 

 bottom. 



13, Lateral view of the posterior extremity of the thorax, much 



enlarged, with its articulated appendages represented only 

 on one side ; the four thoracic segments, /, m, n, o, cor- 

 respond with those represented in fig. 5. In one monstrous 



42 



