_ 48 - 

 Pachastrella ? sp. 



(Plate III, fig. 27.) 



Spicules with three straight slender arms radiating at 

 equal angles and in one plane. The extremities of the arms 

 are not preserved, but they are nearly uniform in thickness 

 throughout, and frequently one is shorter than the other two, 

 but whether this is merely accidental I am unable to say. 

 Average length of arms 0,61 mm. and width 0,045 "ini- ^ot 

 uncommon. 



It is doubtful whether these three - armed spicules 

 are merely spicules in which a fourth arm has not been 

 developed or whether they belong to a different group of 

 sponges than the Pachastrellidae. Mr. Carter states that in 

 P. amygdaloides large triradiates are present in which the 

 fourth arm or shaft is only represented by a short extension 

 of the central canal inside the spicule ; and P. connectens, 

 O. Schmidt (Atlant. Spong. p. 65) is also stated to have large 

 three-rayed spicules; and similar forms are also represented 

 in Sphinctrclla horrida , O. Schmidt (op. cit. p. 65) so that 

 it is not improbable that they may belong to a species o<- 

 Pachastrella. 



Caminus? sp. 



(Plate III, fig. 26.) 



Spicule with three unequal arms in the same plane. 

 One arm is stout, short, and rounded at the extremity, the 

 others are elongated and gradually tapering. Length of shorter 

 arm 0,38 mm.; thickness 0.067 mm. I have onl)' met with 

 a single specimen. The only instance which I have seen of a 

 spicule of corresponding form is represented in Caminus apiariinn, 

 O. Schmidt, (Atlant. Spong. p. 71. Taf VI. fig. 14) from the 

 coast of Florida. The scale to which O. Schmidt's figure is 

 drawn is not stated, so that I am unable to make a comparison 

 as to their relative dimensions. 



