38o 



DISCOVERY REPORTS 



It is naturally impossible to attach these to their aduh species, the only species which 

 can be definitely identified being S. hispidus ; but it may be convenient to set out the 

 possibilities. The following genera of Stenopidea have been described : 



Stenopus, Latreille, 1829 

 Stenopusadus, Richters, 1880 

 Spongicola, De Haan, 1850 

 Spongicoloides , Hansen, 1908 

 Richardina, A. Milne-Edwards, 1881 

 Engystenopus, Alcock, 1895 



No. of species 



Atlantic species 



It is known that Richardina spinicincta has very large eggs (2 x 1-34 mm.), so that it 

 is possible that the larva is hatched in an advanced condition; but it is also at least 

 possible that there is a free larva, as there is in Axius which has still larger eggs. On the 

 other hand, Caullery (1896) states that Spo?igicola koehleri has eggs 2 mm. long contain- 

 ing an embryo with all the appendages, in which case no free larva may be expected. In 

 such circumstances any attempt to attach these larvae to species of adults is out of the 

 question, but the variety of form is so striking that it is of interest to place it on record. 



Table I shows the distribution of the larvae, and it should be noted that many of them 

 were taken on the cruise up the east African coast. The depths of the hauls are given, 

 but as the net was usually brought open to the surface they do not afford good evidence 

 for the depths at which the larvae were taken. 



I have included in the material dealt with in this report a number of specimens found 

 in a sample of plankton taken by the 'Atlantis', the research ship of the Wood's Hole 

 Biological Station, at St. 1121. This sample was left for examination at the Bermuda 

 Biological Station, and I am indebted to Dr Wheeler for permission to handle the 

 decapod larvae contained in it. The sample is remarkably rich in these larvae. 



Stenopus hispidus (Olivier) (Figs. 1-3) 



The larva hatches as an inert prezoea in which the rostrum is bent down under the 

 body, and the setae of the limbs are not protruded. It moults in a few hours into stage I. 



Stage I (Fig. la-j). Length 4-1 mm., including rostrum of 1-3 mm. 



Rostrum with a few small denticles at end. Carapace without supra-orbital spines, 

 rounded behind. Abdominal somite i with pleura drawn out on either side into a long 

 straight spine, and with a small tooth dorsally on either side. Somite 2 without spines. 

 Somite 3 with a pair of lateral spines and a long curved dorsal spine. Somite 4 without 

 spines, but with a few dorsal hairs. Somite 5 with a small dorsal spinous process and a 

 large median ventral procurved process. Telson with small teeth along outer margin, and 

 each angle produced as a stout spine ; posterior margin with five long feathered spines 

 and a short seta on either side. The spine at the angle is evidently homologous with 

 spine I of the normal telson, while spine 2 is reduced as in Thalassinidea and Anomura. 



