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LARVAE OF DECAPOD CRUSTACEA 



PART IV. HIPPOLYTIDAE 



By Robert Gurney, D.Sc. 

 (Text-figures 1-137) 



THE LARVAL GENUS ERETMOCARIS BATE 



HE genus was founded by Bate (1888, p. 895) to include four species of larvae taken 

 in the Pacific near Japan and in the Atlantic near the Cape Verde Islands, all 

 characterized by the great length of the eyestalks. Ortmann (1893, p. 78) described a 

 fifth species, but neither was able to figure the legs, which were all lost. Brooks and 

 Herrick had, however, given excellent figures (1891, pi. ix, x) of a similar larva, probably 

 identical with Eretmocaris stylorostris Bate, as the larva of Stenoptis, and Chun (1888) 

 had described another form under the name of Miersia clavigera. Ortmann recognized 

 that both these larvae belonged to Bate's genus. Lo Bianco (1901, p. 439 and 1909, 

 p. 609) reared from M. clavigera a post-larval stage which he identified as Ligiir edwardsi, 

 but Caroli (19 18) was able to prove that Chun's larva is actually a stage in the develop- 

 ment of Lysmata seticaudata. 



The larva of L. seticaudata is characterized by the great elongation of the eyestalks 

 and the precocious development of leg 5, before the appearance of legs 3 and 4, into an 

 enormously long appendage with a paddle-like enlargement of the propodus. The coxa 

 and basis are correspondingly enlarged, so that even when the rest of the appendage is 

 lost, as it so generally is, it is possible to determine its size in comparison with leg 4. 

 These characters are found in all the four species described by Bate, but Erettnocaris 

 dolichops Ortmann, apparently had leg 5 not larger than leg 4, and no doubt does not 

 belong to the same adult genus as typical Eretmocaris. Whether Bate's four species can 

 be regarded as all belonging to Lystnata is by no means certain, and it is more probable 

 that they represent two or more genera. 



I have had the opportunity of examining a large number and variety of these larval 

 forms from the following sources : 



(i) At Ghardaqa on the Red Sea I obtained a series of stages including one specimen 

 which moulted to the post-larval stage and permits the identification of the series to 

 which it belonged with Lysfnata. Although these larvae agree very closely with those 

 of L. seticaudata I consider their description of value as tending to establish the 

 characters of the genus and to furnish evidence that Eretmocaris is a composite genus. 



(2) From the Great Barrier Reef I have a large material for the use of which I am 

 indebted to Mr F. S. Russell. This material enables me to illustrate certain additional 

 specific types which, so far as can be said at present, seem also to fall within the genus 

 Lysmata. 



