 Like other members of its family , the nursehound is oviparous . Known breeding grounds include the River Fal estuary and Wembury Bay in England , and a number of coastal sites around the Italian Peninsula , in particular the Santa Croce Bank in the Gulf of Naples . Adults move into shallow water in the spring or early summer , and mate only at night . The eggs are deposited in the shallows from March to October . Although a single female produces 77 – 109 oocytes per year , not all of these are ovulated and estimates of the actual number of eggs laid range from 9 to 41 . The eggs mature and are released two at a time , one from each oviduct . Each egg is enclosed in a thick , dark brown case measuring 10 – 13 cm ( 3 @.@ 9 – 5 @.@ 1 in ) long and 3 @.@ 5 cm ( 1 @.@ 4 in ) wide . There are tendrils at the four corners , that allow the female to secure the egg cases to bunches of seaweed ( usually <unk> spp. or <unk> <unk> ) . 
