MAEINE HEMIPTERA (HALOBATES). 155 



When the ovipositor is retracted, the slender basal portions of the hinder gona- 

 pophyses, especially of the inner pair, become bent almost in a semicircle (fig. 19), 

 while the tips of the processes are withdrawn dorsalwards and fit just in front of the 

 anal segment, so that they can be covered by the lateral sclerites of the 8th segment, 

 meeting in the mid-ventral line. 



It has been shown by HEYMONS* that in Naucoris and other Hemiptera the 

 ovipositor is composed of the three pairs of gonapophyses usual in insects, not, as 

 supposed by VERHOEFF,! of two pairs only. Halobates has therefore an ovipositor in 

 which can be recognised all the parts typical of its order and class. But the processes 

 of the 8th segment in Halobates recall by their appearance the outer pair of the 9th 

 segment in Naucoris and in many other insects ; while the latter pair, instead of 

 being as is usual blunt and hairy, form in Halobates stiff, rod-like " guides " for the 

 inner pair of the 9th segment. These last-named processes, which in most hemipteran 

 and hymenopteran ovipositors are closely approximated or even fused together, remain 

 apart in Halobates. Thus the ovipositor has here a somewhat primitive arrangement, 

 intermediate between the simple condition found in the Orthoptera and the specialised 

 form to be observed in such Hemiptera as the Cicadidee. 



The egg of Halobates, which is of large size, must be held between the processes of 

 the 8th segment and the inner processes of the 9th segment. These are the processes 

 that hold the eggs in insectan ovipositors generally. 



If the narrow sclerites above-mentioned (figs. 17, 19, f) represent the skeleton 

 of the 9th abdominal segment, then the "tail-segment" (figs. 16, 17, 19,^) (with 

 which the large dorsal anchor-shaped sclerite in the male presumably corresponds) 

 belongs to the 10th segment, and the small sclerite below it bounding the anal 

 opening (figs. 16, 17, 19, k) represents the llth segment. And thus all the segments 

 of the typical insectan abdomen can be recognised in these remarkable marine bugs, 

 in spite of the many special adaptations that they have undergone in correspondence 

 with their wonderful manner of life. 



* ' Nova Acta Acad. Leopold Carol.,' Ixxiv., 1899, No. 3. 

 t 'Entom. Nachrichten,' xix., 1893, pp. 369-378. 



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