1904] McCLENAHAN : — RHYNCOPHOROUS COLEOPTERA. lOI 



Explanations to the Plates. 

 PLATE VI. 



Fig. I. Adult beetle, Balaninus nasicns Say. 



Fig. 2. Full grown larva of same. 



Fig. 3. Dorsal view of head end of pre-pupa of Mononychus viilpeculus Fabricius, 

 removed from the larval skin, showing foldings of rostrum and antennae, outlines of the 

 developing compound eje, and the fore wing. 



Fig. 4. Ventral view of mouth parts, antennae and rostrum of same. 



Fig. 5. Similar view of Balaninus nasicus. 



PLATE VII. 



Figs. 6, 7 and 8. Three stages in the development of the antenna in the larva of Monony- 

 chus viilpeculus. Fig. 6 is from an old but still active larva; fig. 7 is from a larva in process 

 of metamorphosis; fig. 8 is from a larva near transformation to pupa. 



Fig. 9. Longitudinal section of the club of the antenna of a newly formed pupa of 

 Motionychus vulpeculus. 



«, neuroblastic cell layer, in all the figures of this plate. 



PLATE VIII. 



Fig. 10. Dorsal view of head of newly formed pupa of Motionychus vulpeculus, semi- 

 diagrammatic optic section ; ««/, antenna; t, t, tendons of antennal muscles; s, tip of the 

 chitinous pupal sheath enveloping the entire body ; oe, esophagus ; /ip, hypopharynx; 5,^/, 

 salivary gland; md, mandible; w/.v, maxilla ; ^' and t~, adductor and abductor tendons of the 

 mandible ; //y, hypodermis. 



Fig. II. Similar view of a somewhat older pupa, showing progress in the development 

 of the salivary glands, mandibles and antennae; lettering as before. 



Fig. 12. A divided dorsal view of a dissection of the head of a grown larva of Balaninus 

 nasicus; the right side shows the mandible and its muscles in place; the left side shows 

 these removed, exposing the maxilla and its muscles, the brain and the labial and esophageal 

 muscles. l>r, left cerebral ganglion ; c, nerves going to the mouth parts ; /, 2,j, 4, esophag- 

 eal muscles, detached; ad. m^ and ad. m', adductors of the maxilla; ai>. wi ^, abductor of 

 the maxilla ; ad. tn ^, adductor of the mandible ; ab. m'^, abductor of the mandible ; /, labium ; 

 /. m. labial muscles other lettering as in fig. 10. 



Fig. 13. Frontal section of the tip of the beak in a young pupa of Mononychus vul- 

 peculus; tp abductor, and t,, adductor tendons of the mandible in process of development 

 as invaginations of the hypodermis, hy ; r, chitin ; ;«, pharyngeal process of the mandible 

 budding; other lettering as in fig. 10. 



