648 PATAGONIAN EXPEDITIONS: ZOOLOGY. 



4. In the more narrowed apex of the telson, which may be called sub- 

 acute, and which is a little more produced than in E. gigas. 



Remarks. As regards the third character, given above, the original 

 description of White says that the last joint of the abdomen has, near the 

 base, a slight elevation, grooved in the middle. Stebbing says that there 

 is, on the telson of the specimen he is inclined to refer to this form, a longi- 

 tudinal groove between two elevations, and then a carina running to the 

 end. I have asked for further information from Mr. Stebbing, and, in a 

 letter, he kindly has furnished the additional character, that the last three 

 segments of the peraeon have, along the hind margin of each, four small 

 tubercles. 



Among our material, those specimens called the " smooth form," show 

 exactly the characters given by White and Stebbing : a low elevation on 

 the telson, divided by a groove, and an indistinct median keel running 

 backward, so that there is no doubt that they belong to White's S. 

 lanceolatum. I do not see, however, the four tubercles observed by 

 Stebbing on the peraeon-segments. The pleon and telson of these 

 individuals possess fine granulations. 



As regards S. calcarea of Dollfus, the chief characters are, beside the 

 double keel in the anterior part of the telson, and the single median keel 

 in the posterior, the distinct and prominent granulations on the posterior 

 part of the body, chiefly on the telson. This character is strongly pro- 

 nounced, among our specimens, in those that have been called above the 

 " sculptured form." These granulations are somewhat irregular, and 

 assume sometimes an almost vermiculate appearance. This form also 

 shows the four little tubercles on the hind margins of the three posterior 

 perseon-segments, observed by Stebbing. There is much variety in the 

 degree of development of the granulations. 



The fact that Dollfus mentions a smooth form, and that these two 

 forms, the smooth and the sculptured, also have been found associated by 

 Mr. Hatcher at Santa Cruz and San Julian, while the typical E. gigas is 

 found not at all at these localities ; and further, the fact that among the 

 large number of E. gigas collected by Hatcher at Punta Arenas not a 

 single individual of these forms has been discovered, is much in favor of 

 the view that they really belong together, that is to say, to White's S. 

 lanceolatum. All our specimens from Santa Cruz and San Julian differ 

 in the same four characters, mentioned above, from S. gigas, and further, 



