THE MICROPLANKTON OF PLYMOUTH SOUND. 169 
(12) Portunus sp. zoea (Williamson, C. H., “‘ Report on Larval and Later 
Stages of Certain Decapod Crustacea,” 28th Ann. Rep. Fish. 
Board Scotland, 1907). Many species, begin early in March, 
become very common in April and continue till September, 
less common from October to November, after which they 
disappear. 
(13) Carcinus maenas Leach zoea (Williamson, C. H., “ On the Larval 
and Early Young Stages and Rate of Growth of the Shore Crab ” 
(Carcinus moenas Leach) 21st Ann. Rep. of Fish. Board for 
Scotland, 1903). The first of the Brachyura larve to appear, 
arrives early in January, is specially abundant in February and 
continues till May, after that very scarce. 
(14) Corystes cassivelaunus (Penn.) zoea (Gurney, R., “The Metamor- 
phosis of Corystes cassivelaunus (Penn.),” Q.J.M.S., 1903). From 
the middle of February to July, fairly common, rare in September. 
Brachyura zoea indet. With a long spine like Corystes fairly 
common in September. 
Megalopa indet. Scarce, from May to November. 
PYCNOGONIDA. - 
Norman, A. M., “ The Podosomata (= Pycnogonida) of the Temperate, 
Atlantic and Arctic Oceans,” J. of the Linn. Soc. Zool., Vol. XXX. 
(1) Anaphia petiolata (Kroyer) juv. In June, September and October 
free, with the hind legs not fully developed. In the larval stage 
living in medusz common from July to September. 
(2) Pallene brevirostris Johnston. Occurred once at the end of October. 
Mo.Liusca. 
Polycera quadrilineata (Miill.). Once only in September, 1915. 
Larval Gasteropoda. On and off nearly all the year, commonest in 
July. Rare in mid-winter. 
Larval Lamellibranchiata. On and off, not very common for most of 
the year. Commonest in September, rare in winter. 
LTimacina balea Miller retroversa (Flemm.). Common in the middle 
of September, 1915. Occurred occasionally from July to October. Com- 
mon once in August, 1916. 
