B. VI.] THE HISTOBY OF ANIMALS. 169 



course the males and females begin to assemble, and at the 

 period of intercourse and the production of their ova they pair 

 together. Some of them do not remain pregnant more than 

 thirty days, and others not so long; but all of them remain 

 so for a number of days, which can be distributed into seven. 

 Those which some persons call marini remain pregnant for 

 the longest period. The sargus becomes pregnant in the 

 month of December, and remains so for thirty days. The 

 kind of cestreus which some persons call the chelon and the 

 myxon are pregnant at the same time as the sargus. All 

 these suffer in their pregnancy, wherefore they are driven to 

 the shore at this season; for in the vehemence of their desire 

 they are carried towards the land, and always continue in 

 motion during this period till they have produced their ova. 

 The cestreus is more remarkable for this than any other fish. 

 As soon as they have deposited their ova, they become quiet. 



2. In many fish there is a limit to their reproductive powers, 

 when worms make their appearance in their abdomen. These 

 worms are small living creatures, which expel the repro 

 ductive substance. The small fry of the rhyas makes its ap 

 pearance in the spring, and that of many others about the 

 vernal equinox. Other fish do not produce at this season of 

 the year, but in the summer or near the autumnal equinox. 



3. The atherina produces its young first of all, near the 

 land. The cephalus is the last. This is evident from the 

 small fry of the former appearing first, and that of the latter 

 last of all. The cestreus also produces among the first. The 

 salpa in most places deposits its ova during the summer, and 

 sometimes in the autumn. The aulop as, which they call 

 anthias, produces its ova in the summer season. After these 

 the chrvsophrvs, labrax, mormyrus, and all those which are 

 called dromades ; the trigla and cocarinus are the latest of 

 all the gregarious fish These oviposit in the autumn. The 

 trigla deposits her ova in the mud, which causes her to be 

 late, for the mud continues cold for a long while. The cora- 

 cimus is next to the trigla, and goes among the sea weed to 

 deposit her ova : consequently they frequent rocky places. 

 It continues pregnant for a long while. The ma?nides 

 oviposit at the winter solstice. Many other marine fish 

 oviposit in the summer, for they are not captured at this 

 period. The maenis is the most productive of all fish, aud 



