6 Fishery Board for Scotland. 



While the protozoea may persist for some time after hatching, it seems 

 to be usually a very short stage. In the case of Gelasimus pugnax, 

 according to Faxon, the escape from the egg and the first moult appear to 

 take place simultaneously. 



Cano* says with reference to the Oxyrhynchi — "With the breaking of 

 the shell of the egg the larva evaginates all its spines, and the larval cuticle, 

 reduced to fragments, remains adherent for some time, but it is got rid of 

 with the first movements of larval life." 



The size of the protozoea of holsatus was as follows: — The cephalothorax 

 portion measured in length 'SS-'Smm., and in dorso-ventral extent "Smm. 

 The abdominal portion, which was curved, measured, excluding the plumose 

 appendages, approximately "SS-^Gmm. in length. 



/. Zoea, figs. 25, 85; Abdomen, figs. 15, 18. 



Size. — Distance in a straight line from the tip of the rostral to the 

 tip of the dorsal spine, 1- 25-1- 35 mm.; dorsal spine measured from the 

 hind surface of the carapace, close to the base of the spine, across the 

 arc to the tip, "5 mm. ; rostral spine measured from the anterior border 

 of the eye to the tip, '3 mm.; length of lateral spine, "12 mm.; ab- 

 domen and telson, -92 mm. 



There is no very convenient method of measuring a Zoea, but the 

 distance between the tips of the rostral and dorsal spines is a useful 

 standard. 



I was unable to make out any hairs on the dorsal spine or on the free 

 hind edge of the cai'apace. A hair is present on the carapace on each 

 side of the base of the dorsal spine. In one Zoea two other small hairs 

 were made out close to the preceding. 



The small lobe of the edge of the carapace, named the branchiostegal 

 tooth (brst.), is present (fig. 25). 



The exopodites of the first and second maxilli pedes ha;d each four 

 plumose setae. The buds of the pereiopods and third maxillipede are present, 

 but usually visible only after dissection. The abdomen has no long 

 processes on its segments (fig. 15). Segments 2, 3, 4, and 5 show toothed 

 hind borders. A pair of large studs are present on the second segment, 

 and a pair of very small studs are found on the third segment. 



The pleopods are not visible. A pair of short hairs was found on the 

 dorsum of all the abdominal segments except the first. 



The telson (fig. 18) is a typical structure. 



//. Zoea. 

 This stage is wanting. 



///. Zoea, fig. 12; Abdomen, figs. 10 and 20. 



Size. — Distance in a straight line between the tips of the rostral and 

 dorsal spines, 2-6 mm. ; length of the rostral spine beyond the eye, 

 •85 mm. ; length of carapace, -8 mm. ; length of abdomen, including 

 telson, about 1 '6 mm. 



This stage difiers from the I. Zoea in the structure of the abdomen 

 (fig. 10). The hind edges of the third, fourth, and fifth segments are pro- 

 duced into spines. That of the fifth segment is not yet very large. The 

 studs are present on both the second and third segments, and a suggestion 

 of a stud was made out on the fourth segment also. The developing 

 pleopods are now visible (pi, figs. 10 and 20.) The sixth abdominal 



* Cano: " Sviluppo e Morfologia degli Oxyrhynchi." Mittheil. Zool. Stat. Neape 

 10 Bd., 1891-1893, p. 27. 2 plates. 



