THE society's note-books. 253 



EXPLANATION OF PLATES XLII. AND XLIU. 



PLATE XLII. 



Fig. 1. — Saw of a common Black Saw-Fly, mag. 33 diam. 

 ,, 2. — Tip of the same, mag. 83 diam., showing serrature of the 



teeth, and groove in which the back-piece works. 

 ,, 3. — Saw of another Saw-Fly. Teeth not serrated, showing the 

 curious mode in which they are strengthened by the thicken- 

 ing of the blade in certain bars. Drawn by H. M. J. 

 Underhill, from specimens in his cabinet. 



4. — Foot of a large Green Saw-Fly, (Allantus,) mag. 31 diam. 

 , The pads, which, in their natural position, are on the under- 

 side of each joint of the tarsus, have become distorted in 

 mounting, and are shown on the left-hand side of drawing. 



b, soft and probably adhesive portion of the terminal pad ; 



c, hard part of the same pad acting as a lever, to which 

 muscles are attached ; d, projection under the foot forming 

 a socket into which the pad may be partially withdrawn ; 

 e, thickening of the chitine. Drawn by F. J. Allen. 



,, 5. — Hind leg of Glow-Wonn, ^. The organs marked a are 

 those respecting which information is asked. 



Drawn by H. Basevi. 



,, 6. — Lahidostomma luteum. 



,, 7. — One of the chelate mandibles of the same. 



Drawn by C. F. George. 



PLATE XLIIL 



Fig. L — Sectional diagram of the Sea-Fir (Sertidaria) : c.c, the horny 

 covering which supports and gives strength to the entire 

 organism, and which expands to form the horny cups in 

 which the little animals reside ; rn.m., the mouths surrounded 

 by tentacles t.t., lead into a simple body-cavity, b.c. ; ec, 

 the ectodern ; eu. , the endoderm layers of the body; a.a., 

 the hollow into which the body-cavity of each separate animal 

 leads, thus forming a free communication with the whole 

 colony. 

 Figs. 2, 3, 4. — Receptacles, in various stages of maturity, developed on 

 the branches of the Sertidaria, from which true eggs are dis- 

 charged. 

 Fig. 5. — A free-swimming egg in two stages. 



, , 6. — An egg settled down. 



J, 7. — A bud-like projection developed from it, and growing into 



,, 8. — A single hydra-like animal, which becomes the founder of 



,, 9. — A new colony, 



,, 10. — Small portion of Sertidaria abietina, mag. 25 diam. 



,, 11. — Small portion Sertidaria 2}lurna, mag. 25 diam. 



,, 12. — Small portion Sertidaria lendigera, mag. 25 diam. 



,, 13. — Portion of Sertidaria, as it appears to the naked eye. 



