14 Addis on E. Verrill, 



transverse riblets, with a longitudinal undulation. Close to this 

 is a small, smooth, oblong knob, which fits into a groove on the 

 inner edge of the smooth rib of the fixed basal segment, along 

 which the stridulating organ slides, when the antenna vibrates, and 

 this serves to hold the organ in position. External to the stridu- 

 lating plate the basal edge of the segment forms a small, concave, 

 stiff lobe, with a transverse groove. This slides back and forth 

 on the upper side of the smooth rib of the basal segment during 

 stridulation, and like the knob and groove, serves to hold the organ 

 in place. 



This organ was described by Dr. G. Browne Goode (op. cit. 

 1878) as follows: "The 'Bermuda lobster' (Panulirus amcricamis 

 M. Edw.) makes a loud grating noise. Mr. Kent describes the 

 voice of the allied species (Palinurus quadricornis) as being pro- 

 duced by the rubbing together of the spinous abdominal segments. 

 In the species observed by me, the sound was produced by means 

 of certain modifications of the lower joints of the antennae. There 

 is, at the base of each antenna, upon the anterior part of the 

 cephalothorax, a broad elevated ridge, parallel with the axis of 

 the body, which in an adult of eighteen inches would be about two 

 inches long. The rounded crests of these ridges are closely 

 embraced by processes from the sides of the basal antennal seg- 

 ments. The profile of each ridge describes the segment of a circle, 

 the center of which is the center of articulation of its accompanying 

 antenna. When the antennae are moved forward and backward, 

 their tips waving over the back of the animal, the close contact of 

 the hard, smooth, chitinous surfaces produces a shrill, harsh stridu- 

 lation, like the sound of filing a saw. 



I never heard the noise when the animals were under water, 

 though I have seen them waving their antennas. I have no doubt 

 that they can thus produce vibrations perceptible to their mates at 

 great distances, especially if their other senses are as acute as that 

 of smell, which I have tested in a very curious manner. Both 

 sexes are provided with the vocal organs." 



Living specimens of this species were formerly brought from 

 Bermuda to the New York Aquarium, but they usually lived only 

 a very short time, owing to the impure harbor water then used. 



Their bright colors and interesting habits make them very desir- 

 able in a public aquarium, but they are very sensitive and need 

 the purest sea water. More recently several of good size were 



