Fig. 61. Hydrophorus albiceps Frey	Fig. 62. Hydrophorus alpinus Wahlberg
Fig. 63. Hydrophorus balticus (Meigen)	Fig. 64. Hydrophorus bipunctatus (Lehmann)
Fig. 65. Hydrophorus borealis Loew	Fig. 66. Hydrophorus brunnicosus Loew
Fig. 67. Hydrophorus callostomus Loew	Fig. 68. Hydrophorus freyi Storå
Fig. 69. Hydrophorus geminus Frey	Fig. 70. Hydrophorus litoreus Fallén
Fig. 71. Hydrophorus signifer Coquillett	Fig. 72. Hydrophorus nebulosus Fallén
Fig. 73. Hydrophorus norvegicus Ringdahl	Fig. 74. Hydrophorus oceanus (Macquart)
Fig. 75. Hydrophorus pectinatus Gerstäcker	Fig. 76. Hydrophorus pilipes Frey
Fig. 77. Hydrophorus rufibarbis Gerstäcker
Fig. 78. Hydrophorus viridis (Meigen)
Fig. 79. Hydrophorus altivagus Aldrich	Figs. 82 (1-5). Hydrophorus praecox (Lehmann)
Fig. 80. Hydrophorus rogenhoferi Mik	Fig. 81. Hydrophorus praecox  (Lehmann)

Figs. 61-81. Hydrophorus spp. Hypopygium, left lateral view (after Negrobov, 1977-1979).

Figs. 82 (1-5). Variation of hypopygium structures in Hydrophorus praecox Lehmann. 1-2, hypandrium, lateral view; 3-5, dorsal lobe of surstylus, ventro-lateral view (orig.).