30 MR JAMES MURRAY 



Richters (9), but this does not indicate any affinity whatever, as the entire organisation 

 is different. The processes in that species are divided into several points, but they are 

 not dichotomous. 



Macrobiotus echinogenitus, Richters. (Plate IV. figs. 14a and 146.) 



A single egg, the largest seen, might belong to this extremely variable species, but 

 no adult animal at all resembling M. echinogenitus in structure was found. 



The egg measures 102 M without the spines, 120 M over the spines. 



The processes are conical, with rounded tops. They are not unlike those figured by 

 Plate as the egg of M. hufelandi (5). 



It is only on account of the great variability of the egg of M. echinogenitus, in size 

 as well as in the form of the processes, that I for the time being include this large egg 

 under that species. I expect to find that the animal which produces this egg is a 

 distinct species. 



In a previous paper (4) dealing with M. echinogenitus, I was led by an error in trans- 

 lation to entirely misrepresent Professor RICHTERS' work on this species and M. hufelandi. 



In reading his original description (9), I understood Professor RICHTERS to say that the 

 two species were so close that they could only be separated by the totally different form 

 of their eggs, and so omitted to read carefully the remainder of the description, in which 

 he shows that both claws and pharynx are quite different in the two species. The claws 

 of M. hufelandi are joined for half their length, those of M. echinogenitus form a V, 

 jointed only as the bases. The pharynx of M. echinogenitus is variable, presenting three 

 distinct forms, each associated with a different size of egg. If other species, as is likely, 

 have also series of distinct forms of pharynx, the value of this otherwise excellent 

 character for specific distinction is lessened. Everything has yet to be learned as to the 

 cause and meaning of this variation, especially of the remarkable ' simplex ' form. 



I have seen hatch from a sufficiently typical hufelandi egg an animal with a pharynx 

 like one of the forms figured by RICHTERS for echinogenitus (13, Plate 16, fig. 16). 



The claws appear to be the least variable structures of Macrobiotus, and by their 

 form M. hufelandi and M. echinogenitus can be most readily distinguished. 



Macrobiotus, sp. ? (Plate IV. figs. 15a to 15c.) 



This species we only know from the egg, the very distinct structure of which 

 indicates a good species, but none of them contained a fully developed young, so the 

 identification could not be completed. The processes consist each of a hemispherical 

 base, from the summit of which rises a pair of ovate bodies resembling leaflets, which 

 meet below and diverge above. The egg measures 80 /u without the processes, and 95 M 

 over them. 



(ROY. soc. EDIN. TRANS., VOL. XLV., 328.) 



