LARVAE OF DECAPOD CRUSTACEA 395 



the posterior diverticula of the stomach. Suhm's "testis" is a structure easily seen in 

 most of the older specimens. It runs across the front of the heart, and is generally filled 

 with granular matter, or occasionally with large cells having the appearance of ova. On 

 each side it turns sharply backwards and can be traced as a slender strand to the region 

 of leg 5. In one case I have seen these strands leading apparently to leg 3, and in this 

 case the cells of the organ were larger than usual. The organ has the appearance of a 

 developing gonad, but it is unaccountable that it should so generally run to leg 5, 

 for it is unlikely that so large a percentage of the specimens should be males. 

 Whatever the nature of this organ is, it is of no very great importance, since Amphioii is 

 most certainly not a mature animal, even though it may be proved to have a developing 

 gonad. 



Distribution. 



The Discovery material oi Amphion consists of ninety-seven specimens, most of which 

 were taken at twenty-six stations in the Atlantic along the meridian of 30° W from 

 30° S to nearly 33° N. Other stations are in the region of the Canaries and in the 

 equatorial region. In addition there was an isolated capture at St. 85, west of the Cape 

 in about 5° E long., and six along the east coast of Africa. The localities are given in 

 Table II. 



All appear to belong to a single species. In nearly all cases a minute rostral spine is 

 present, and also a procurved post-rostral spine which is the termination of a slight 

 dorsal ridge. Bate distinguished the Atlantic from the Pacific form as follows : 



Rostral spine present, but no post-rostral 

 Rostral spine absent; post-rostral present 



A. reynaudi, M.-Edw., Pacific. 

 A. provocatoris, Bate, Atlantic. 



Ortmann (1893) has already pointed out that both spines are present in the Atlantic 

 form, and he therefore rejected Bate's species. In the Discovery material the rostral 

 spine is sometimes absent, but the post-rostral is always present, except in very young 

 specimens when it is represented by a simple protuberance in both Atlantic and 

 eastern specimens. 



The vertical distribution cannot be determined from the Discovery samples, since 

 the net was fished open to the surface. Taking the maximum depths of the hauls in 

 which Amphion was captured the distribution was as follows : 



3-2 



