440 MR. LUBBOCK ON THE THYSANURA. 



shaped sometliing like a pear, and attached by its larger extremity. It bears four or five 

 short hairs. Attached to it is a second piece, also of a pyriform shape, but with the apex 

 divided into two lobes. When the spring is turned forwards, the base ends close to 

 this organ, exactly as described by M. Nicolet. 



The basal part of the spring, that is to say, the part measured from the fold which 

 separates (if my suggestion is correct) the first from the second abdominal segment, is 

 ■0125" in length ; the middle part is -022" in length, with a breadth of -002" at the base, 

 and -002" at the extremity ; while the terminal segment is -0075" in length, and -00125" 

 in width at the base. It tapers a little towards the extremity, and has from 30 to 40 

 small teeth on its inner margin. 



The distribution of the hairs resembles that of the preceding species. 



The haks on the posterior part of the abdomen are of two sorts, some (PI. XLVI. fig. 34) 

 being short and sword-shaped, while others are longer, and resemble a lady's riding- whip. 



The males may be distinguished from the females, so far as my observations went, only 

 by the presence of a small papilla on the ventral surface, just in front of the anus. 



On the Anatomy of the SmynthuridtE. 

 Smi/utlmms JBuskii. 



Digestive Organs. — The intestinal canal is a straight tube, and falls into three divisions 

 — the oesophagus, the stomach, and the rectum. The oesophagus is ratlier long, narrow, 

 and composed, as apparently in most of the Thysamxra, of an inner chitinous membrane 

 and an outer layer containing muscular fibres. The stomach extends almost the whole 

 length of the thorax and abdomen. It is a capacious sac, and is lined internally by 

 yeUow nucleated cells, resembling the so-called liver-cells of some lower Invertebrata. 

 They are about -005" in diameter, and tolerably uniform in size. They are themselves 

 colom-less, but contain a great number of minute yellow globules, resembUng oil-globules. 

 The nuclei, when freed from the surrounding matter, are clear vesicles about -002" in 

 diameter, and contain a very few minute granules. The contents of the stomach con- 

 sisted, in my specimens, altogether of spores and young shoots of Cryptogams. The 

 rectum is quite short, and, like the stomach, is provided with longitudinal and transverse 

 muscles. The former, however, are not easy to distinguish. The digestive organs of the 

 Thysanura are very uniform; at least, in addition to the genus Smynthurm, 1 have 

 examined specimens of Isotoma, Degeeria, Lipura, Macrotoma, and Lepidocyrtus, with- 

 out finding any great diff'erences. M. Nicolet also gives one description of tlie digestive 

 organs as applicable to all the Poduridse (including Smynthurus), but he takes a very 

 diff'erent view of the subject. 



The digestive organs of the Poduridse, according to him, are composed of five parts, 

 " I'esophage, le jabot, le ventricule chylifere, les vaisseaux hepatiques, I'intestin grele, 

 et le caecum." He admits, however, that " le jabot parait n'etre qu'une simple dilata- 

 tion de I'esophage, dont le diametre varie selon que I'insecte a plus ou moins mange;" 

 it has also no different structure from the rest of the oesophagus, and cannot therefore be 

 compared with the true "jabot " of other insects. M. Nicolet mentions the longitudinal 

 muscles on the stomach, and has also noticed the transverse fibres, which, however, he 



