1 91 Prof. J. O. Westwood's Notes, §-c. 



a very short basal and a longer elongate-ovate terminal 

 joint. The antennse are represented (his fig. 14) as 

 4-jointed and cylindrical, the joints gradually shortening 

 to the tips. 



My object in the preceding observations has been to 

 describe the precise structure of the singular creatures 

 under examination. I by no means wish to disparage, in 

 the slightest degree, the value of the admirable deduc- 

 tion which Messrs. Joly have arrived at as to the insect- 

 nature of Prosopistoma, founded on the examination of 

 recent specimens. Further, with the example of my 

 Branchiotoma Spongillce. (now ascertained to be the larva 

 of one of the Hemerohiida) before us, we need scarcely be 

 surprised if Prosopistoma should prove to be the larva of 

 an Ephemerideous fly. Its whole character is, however, 

 so anomalous and unlike that of any other Ephemerideous 

 larva, that direct observation alone of its transformations 

 will be required to confirm the opinions of Messrs. Joly. 



DESCRIPTION OF THE EIGURES. 

 PLATE IV. (Division B.) 



Eig. 1. P)-osopi.stoma variegatum,, magnified ; seen from above. 



Eig. 2. The same, ventral surface. 



Fig. 3. One of the six legs of ditto. 



Fig. 4. One of the maxillse terminating in a group of four strong curved 

 bristles, with a single one detached. The long basal piece on 

 the right side of the figure may possibly be extraneous. 



Eig. 5. Extremity of the body of P. punctifrons. (From M. Joly.) 



PLATE V. 



{Copied from the figures inihlisheci hy Messrs. Joly.) 



Eig. 1. Prosopistoma punctifrons, magnified. From " Annales des Sci. 



Nat. Zool.," Ser. V., Zool., vol. xvi., pi. 13, shewing, a, the trophi, 



m, the 'levre inferieure' or 'espece de masque,' and 1,2, 3, i, 5, 



the first five segments of the abdomen. 

 Fig. 2. Underside of the head. 

 Fig. 3. The labrum. 

 Fig. 4. One of the mandibles. 

 Eig. 5. One of the maxillge. 

 Eig. 6. The labium with its palpi. 

 Eig. 7. One of the antennae. 



Eig. 8. Portion of the tracheo-branchial apparatus. 

 Eig. 9. The two valves of the posterior margin of the carapace, shewing 



the minute carmine molecules which escaped with the water used 



in respiration. 

 Fig. 10. The corrected figure of the same animal (from the "Eeuille dcs 



Jeunes Naturalistes," 1st March, 1876) ; seen from above. 

 Eig. 11. The same (from ditto) ; seen from below. 

 Eig. 12. The terminal segments of the body ; seen from above. (From 



the " Annales des Sci. Nat.") 



