FISHERY BULLETIN: VOL. 77. NO 2 



Table 4. — One-way analysis of variance on short carapace 

 length otStereomastis nana and S sculpta by sex imale. female, 

 and ovigerous female). 



ITH SPERMATQPHORES PRESENT 



'SS = sum of squares 

 ^MS = mean squares 

 ■*P 01 



Table 5. — Percent of ma\e Stereomast is nana by size interval. 

 Size groupmgs result from chi-sqirare analysis of male and 

 female frequencies by 2 mm size intervals. 



SHORT CARAPACE LENGTH (mm) 



Figure 2. — Length-frequency distribution ofStereomastis nana 

 pooled for all months of collection. 



3 ). Immature ovaries were threadlike and difficult 

 to remove from the specimens because of their 

 adherence to the dorsal portion of the digestive 

 gland. In cross section, the oocytes appeared very 

 small (0.05-0.2 mm, mean =0.1 mm) with the 

 nucleus composing most of the oocyte. Resting 

 ovaries had oocytes (0.1-0.3 mm, mean = 0.2 mm) 

 with a large nucleus and no yolk granules (Figure 

 4A). The intermediate ovary had fewer densely 

 packed oocytes (0.1-0.4 mm, mean = 0.3 mm). A 

 distinct basophilic nucleus with condensed 

 chromosomes was visible in cross section. Yolk 

 granules partially filled the cytoplasm. The ger- 

 minative zone was well developed and filled with 

 developing, basophilic oocytes (Figure 4B). In the 

 ripening ovary, the oocytes were irregularly 

 shaped (0.3-0.8 mm, mean = 0.5 mm), with the 

 cytoplasm partially filled with yolk granules. 

 There was a visible nucleus. The germinative area 

 within the ovary was larger than in ripe individu- 

 als. In gravid individuals, the ovary occupied 

 much of the thoracic cavity, with anterior and 

 posterior horns extending laterally. The oocytes 

 (0.5-0.9 mm in diameter, mean = 0.7 mm) were 

 tightly packed and irregularly shaped, yet they 

 were easily dislodged from the ovary with slight 

 probing. Histological sectioning revealed oocytes 

 to be filled with yolk granules. The nucleus was 



generally not visible and the central germinative 

 zone of the ovary was compressed (Figure 4C). 

 Individuals with ovaries judged to be spent were 

 usually ovigerous females. The ovaries contained 

 a few atresic (0.3-0.4 mm) oocytes, but much of the 

 ovary was filled with resting stage basophilic oo- 

 cytes (0.1-0.2 mm (Figure 4D)). 



Most nonovigerous females <26 mm had imma- 

 ture and resting ovaries (Figure 5). Individuals 

 with ripening and gravid ovaries first appeared at 

 21 mm, and the percentage of females in these 

 stages increased with increasing size. Approxi- 

 mately 58"^'^ of the 65 nonovigerous females with 

 external spermatophores were ripe. The remain- 

 ing individuals had immature (&7c ), resting (99f ), 

 intermediate 1 1 1'* ), ripening (8'^? ), or spent (8'? ) 

 ovaries. A large percentage of ovigerous S. nana 

 21 mm or larger were spent, but there were some 

 ovigerous individuals with ovaries in each stage of 

 development (Figure 5). In most cases, ovigerous 

 females with ripening or gravid ovaries had ad- 

 vanced eggs (eyes and a discernible abdomen), cor- 

 responding to C or C+ stage designated by 

 Meredith ( 1952). Spent individuals had eggs that 

 were newly deposited (stages A-A-(-) or gastru- 

 lated (stage B + ). 



Ovigerous and other female S. nana with exter- 

 nal spermatophores attached were found during 



438 



