. The Canadian field-naturalist. 1978 Notes 83. Figure 1. Map of the six areas in Annapolis and Kings Counties where Onchidoris bilamellata was collected. Major sites are 1, Cape Blomidon; 2, Kingsport; and 3, Black Rock. Of lesser importance were 4, Port George; 5, Hampton; and 6, Port Royal. Minas Basin study sites. Cape Blomidon and Kings- port, have been published previously (Bleakney and McAllister 1973; Bleakney and Mustard 1974). Methods Our general collections of nudibranchs taken at extreme low tides were begun on a year-round basis in 1967, although the annual emphasis varied relativ
. The Canadian field-naturalist. 1978 Notes 83. Figure 1. Map of the six areas in Annapolis and Kings Counties where Onchidoris bilamellata was collected. Major sites are 1, Cape Blomidon; 2, Kingsport; and 3, Black Rock. Of lesser importance were 4, Port George; 5, Hampton; and 6, Port Royal. Minas Basin study sites. Cape Blomidon and Kings- port, have been published previously (Bleakney and McAllister 1973; Bleakney and Mustard 1974). Methods Our general collections of nudibranchs taken at extreme low tides were begun on a year-round basis in 1967, although the annual emphasis varied relative to species and habitats. Table 1 summarizes a 10-year accumulation of observations of bilamellata. During field excursions, populations of O. bilamel- lata were often observed but not collected particularly if we already had data from that time period. Thus the many blanks in Table 1 do not necessarily indicate the species' absence nor a cessation of field activities for that month. Only representative size-range samples were collected because any regular intensive collecting aimed at determination of population size-class changes could decimate local restricted populations. At any one time most individuals were similar in size and after collecting several of these efforts were concentrated on finding any larger or smaller speci- mens. This size range information, based on 58 collections totalling 453 specimens, is presented in Figure 2. Results and Discussion It is evident from the information provided by Potts (1970) and by our observations in Nova Scotia, that O. bilamellata is an annual species but the basic pattern is not rigidly fitted to calendar months. For example. Potts determined that in 1964 the adults were absent from 10 May to 30 July but in 1965 they were absent for a 6-month period from 29 April to 16 October. Similarly, in Nova Scotia 1969 was excep- tional. Spawn from this species has been found in all months from January through July (Figure 2), but on 16 f
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