Cleaning behaviors of L. dimidiatus and requesting displays of 36 species of fishes belonging to 23 families were studied in a large tank (350m^3) of the Suma Aquarium in 1964 and 1965. Results are;1) most of the species distributed on the rocky or coral reefs of the tropical and temperate Pacific displayed the requesting behavior to L. dimidiatus. 2) Offshore sandy bottom dwellers (three species of sharks and a conger eel) did not request. 3) Only one species, the rainbow trout (Salmo gairdneri), which had been accrimated to salt water, showed aggressive behavior to the L. dimidiatus. 4) From these facts, it may be said that the relationships between L. dimidiatus and requesting fishes has developed through their symbiotic coactions during the long geologic time.
Morphological comparisons were made between the adult females of Culex pipiens pallens COQUILLBTT and C. vagans WIEDEMANN obtained from full grown fourth instar larvae and/or pupae collected at various breeding sites in the northern parts of Japan. A primary diagnostic character for separating the adult females of C. vagans from C. p. pallens used in this paper is the white stripe (s) on the leg (s). Variation in the appearance of the character is recognized in C. vagans. Morphological comparisons between the two species collected at the same breeding sites were made by examining the following characters ; R cell length (=(R_2+R_3)/2), R_2 petiole length, (R cell length)/(wing length)×1000,(R_2 petiole length)/(wing length)×1000,R-ratio (=(R cell length)/(R_2 petiole length)×100), M cell length (=(M_<1+2>+M_<3+4>)/2), M_2 petiole length, (M cell length)/(wing length)×1000,(M_2 petiole length)/(wing length)×1000,M-ratio (=(M cell length)/(M_2 petiole length)×100), wing length, wing width, L/W-ratio (=(wing length)/(wing width)), number of the ninth tergite setae, and number of the insula setae. The variation ranges of all the characters used for the comparison were overlapped between the two species. Eleven characters (excluding M cell length, (M cell length)/(wing length)×1000,wing length, and wing width from the above) were considered to be useful for the comparison between the two species. For further comparison, a tentative method was used by giving emphasis to each character, based on the significant level of the difference of the means between the two species. Applying the method mentioned above, it is concluded that the morphological difference between the two species is more distinct at the typical larval habitat (natural water bodies) of C. vagans than at the breeding site artificially polluted. This conclusion agrees with that obtained in the study by the author concerning the larval characters between the two species.