POST-LARVAL STAGES OF JASUS LALANDIl. 117 



stage. One characteristic seems to indicate that it is not so, namely, its 

 much greater total length (from anterior end oi carapace to posterior end of 

 telson) than that of the piierulus or even later stages of Jasus lalandii, and 

 this objection seems to be further strengthened by the recent observations of 

 Bouvier (1) on the larval stages of Palinurus vulgaris. He has found what 

 he regards as a complete series of stages between the early phyllosomas and 

 the puerulus stage, there being a gradual increase in size in the total length, 

 that of the oldest phyllosoma being equal to that of the puerulus. The 

 objection, however, disappears when we remember that the total length of 

 the phyllosoma includes the head region between the anterior end and the 

 first maxillipedes. This region, which is nearly half the total length in a 

 phyllosoma of 35 mm., must become enormously reduced before the adult 

 stage, to whatever genus or species it may belong, is reached. The thoracic 

 region also becomes relatively shorter as we advance from the first phyllo- 

 soma stage, and the only test of age in terms of length would appear to be 

 in the abdominal region. 



Puerulus of 22-26 mm. (PL 12 ; [Fig. 32] PL 17.) 



This stage is transparent, but has still the characteristic red spots of th» 

 phyllosoma. These are very marked in the living state, but soon disappear 

 on the death of the animal, if not kept in darkness. They occur chiefly on 

 the under side of the body, as shown in the figure (PL 12), which was 

 drawn by Mr. Birbel soon after the animal was captured. 



The carapace on its upper surface is almost flat, being slightly convex in 

 the cardiac region. The sides are bent downwards so as to be almost at 

 right angles to the upper surface, but there is no very distinct ridge between 

 sides and upper surface. Posteriorly the sides are not so well developed, 

 and leave the gills partly exposed. There are slight but distinct traces of a 

 cardiac and a pair of branchial grooves. 



A few spines only are present. The most outstanding are the frontal or 

 post-rostral. They project over the bases of the eye-stalk, pointing forwards 

 and slightly inwards. Immediately behind them is a smaller pair, projecting 

 forwards over the bases of the first. A little to the outside of this second 

 pair, and behind the middle of each eye-stalk, is a somewhat larger (gastric) 

 spine, behind which, and a little towards the side, is a strong (branchial) 

 spine, from which the lateral ridge commences. Below the eye in the 

 hepatic region is a strong spine. There is a single low median spine over 

 the gastric region, and, posterior to it, towards the cardiac region, a pair of 

 small spines, between which and the ridge spine is another small spine over 

 the branchial region. Thus there are two pairs of frontal spines, three 

 gastric, two cardiac, two pairs of branchial, one hepatic, corresponding to 



LINN. JOURN. — zoology, VOL. XXXIII. 9 



