Moesz Gusztáv - Soós Lajos (szerk.): A Magyar Természettudományi Múzeum évkönyve 28. (Budapest 1934)

Hungerford, H. B. ; Evans, N. E.: The Hydrometridae of the Hungarian National Museum and other studies in the family. (Hemiptera)

4. Thoracic and acetabular pitting, their absence or presence .and their character. 5. Form of clypeus. 6. Proportional distances of the coxae inter se. 7. Extension of the anterior and posterior femora as compared to the apex of the head and the tip of the abdomen respectively. 8. Comparative length of the head and antennal segment II. 9. Male ventral processes of the sixth or seventh segments of the abdomen. 10. Terminal segment of the male abdomen. 11. Length. To the above Dr. T. JACZEWSKI (10) 1928 has added the information that the male claspers of H. Husseyi BUENO and H. Sztolemani JACZEWSKI are different. The anteocular part of the head is considered as extending from the very tip of the clypeus to the anterior margin of the eyes, while ihe postocular part is measured from the posterior margin of the eyes to the anterior margin of the pronotum. The head of the specimen must be in its natural position if the measurements are to be accurate. The rostrum appears to be quite flexible and sometimes is quite difficult to measure accurately due to its curvature. Antennal segments I and II are stiff and straight and are easily measured. The third segment. however, is very frequently curved or sinuate and is often missing. The presence or absence of pits on the pronotum and acetabula and their arrangement seem to be characteristic, although some variation in number may occur on the two sides of the same insect in some groups. In other groups the number and arrangement of the pits are most constant. The distance between the coxae is more properly the distance from the anterior margin of each acetabulum to the anterior margin of the acetabulum immediately behind. The presence or absence, the position and structure, of the male abdominal processes are very good characters. Considering that the proportions of the antennal segments inter se are being used in taxonomic work, it was considered worthwhile to measure as accurately as possible the lengths of the antennal segments of a series of specimens in order to see how much variation there was present. Accordingly, the antennal segments of fifty males and fifty females of Hydrometra Martini KIRKALDY were measured. These had been eoJlected in October from ihibernating quarters near a very small pool. The measurements were made with the aid of an eyepiece micrometer with fifty divisions to the millimeter.